Gas meter

Abstract

To provide a technology that can reduce gas pressure loss in gas meters.SOLUTION: The gas meter comprises a tubular measurement flow path section through which the gas to be measured flows, a flow rate measurement section that measures the flow rate of the gas flowing through the measurement flow path section by irradiating ultrasonic waves into the measurement flow path section, a buffer chamber in which the inlet of the measurement flow path section is located and which guides the gas to the inlet of the measurement flow path section, an upstream flow path section that forms a flow path that guides the gas to the buffer chamber, and at least one guide wall section that protrudes from the inner wall surface of the buffer chamber around the inlet of the measurement flow path section in a region outside the inlet of the measurement flow path section when the buffer chamber is viewed in the direction of the central axis, and has a portion that extends toward the inlet side of the measurement flow path section in a region forward of the inlet of the measurement flow path section when viewed in a direction perpendicular to the direction of the central axis.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology of the present disclosure relates to a gas meter. [Background technology]

[0002] A known type of gas meter is an ultrasonic gas meter that uses ultrasonic waves to measure the flow rate of gas. Hereinafter, the term "gas meter" will be used to refer to an ultrasonic gas meter. A gas meter typically has a tubular measurement flow path through which the gas to be measured flows. It measures the flow rate of gas by irradiating ultrasonic waves into the measurement flow path through which the gas flows and measuring the time required for the ultrasonic waves to be transmitted and received.

[0003] Conventionally, various innovations have been made in the structure of the internal gas flow path of gas meters. For example, Patent Documents 1 and 2 listed below adopt a gas flow path configuration in which the gas flow is bent and turned back in a roughly S-shape just before the inlet or outlet of the measurement flow path section to suppress the generation of turbulent gas flow within the measurement flow path section, which can cause a decrease in measurement accuracy. Also, Patent Document 3 listed below forms protrusions that protrude toward the measurement flow path section on the wall surfaces facing the inlet and outlet of the measurement flow path section so that the gas can be rectified at the inlet and outlet of the measurement flow path section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-17499 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-10414 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-232942 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technologies of Patent Documents 1 and 2, the gas flow is turned back in an approximately S-shape just before the measurement flow path, which increases the length of the gas flow path, potentially increasing gas pressure loss. Furthermore, in the technology of Patent Document 3, the protrusion provided just before the inlet of the measurement flow path may narrow the gas flow path near the inlet of the measurement flow path or bend the gas flow direction, potentially increasing gas pressure loss when the gas flows into the measurement flow path. Thus, conventional gas meters still have room for improvement in reducing gas pressure loss in the gas meter by reducing gas pressure loss when the gas flows into the measurement flow path. [Means for solving the problem]

[0006] The technology of the present disclosure can be realized in the following forms.

[0007] [First Form] The first form is provided as a gas meter. The gas meter of the first form includes a tubular measurement flow path section through which a gas to be measured flows, a flow rate measurement section that measures the flow rate of the gas flowing through the measurement flow path section by irradiating ultrasonic waves into the measurement flow path section, a buffer chamber in which an inlet of the measurement flow path section is disposed and which guides the gas to the inlet of the measurement flow path section, an upstream flow path section that forms a flow path for guiding the gas to the buffer chamber and is connected to an end region of the buffer chamber that is shifted from the central axis when the buffer chamber is viewed in the direction of a central axis of the inlet of the measurement flow path section from a direction perpendicular to the central axis, and at least one guide wall section that protrudes from an inner wall surface of the buffer chamber that surrounds the inlet of the measurement flow path section in a region outside the inlet of the measurement flow path section when the buffer chamber is viewed in the direction perpendicular to the central axis and has a portion that extends toward the inlet of the measurement flow path section in a region just before the inlet of the measurement flow path section when viewed in the direction perpendicular to the central axis. According to the gas meter of the first aspect, the guide wall portion provided on the inner wall surface of the buffer chamber around the inlet of the measurement flow path portion can guide gas to the inlet of the measurement flow path portion, thereby smoothing the flow of gas flowing into the measurement flow path portion. This reduces the pressure loss of gas when it flows into the measurement flow path portion, and reduces the pressure loss of gas in the gas meter.

[0008] [Second mode] In the gas meter described in the first mode, when the buffer chamber is viewed in the central axis direction, a plurality of the guide wall portions may be formed around the inlet of the measurement flow path portion. According to the gas meter of the second aspect, the multiple guide walls around the inlet of the measurement flow path section can increase the number of gas paths from the buffer chamber to the inlet of the measurement flow path section, further facilitating the flow of gas into the inlet of the measurement flow path section, thereby further reducing the gas pressure loss in the gas meter.

[0009] [Third Form] In the gas meter described in the first or second form above, the inlet of the measurement flow path section is positioned at a position protruding from the inner wall surface of the buffer chamber in the direction of the central axis, and the guide wall section may extend from a region in front of the inlet of the measurement flow path section to a region behind it when viewed in a direction perpendicular to the direction of the central axis. According to the gas meter of the third aspect, the guide wall portion makes it easier to guide the gas around the inlet of the measurement flow path portion to the inlet of the measurement flow path portion, thereby further reducing the gas pressure loss in the gas meter.

[0010] [Fourth Form] In the gas meter described in any one of the first, second, and third forms, the guide wall portion may include an inlet guide wall portion that protrudes at the inlet of the buffer chamber to which the upstream flow path portion is connected so as to face the outlet of the upstream flow path portion. According to the fourth form of gas meter, the inlet guide wall portion can form a gas flow from the inlet of the buffer chamber toward the inlet of the measurement flow path portion, thereby further smoothing the flow of gas flowing into the inlet of the measurement flow path portion.

[0011] [Fifth Form] In the gas meter described in any one of the first, second, third and fourth forms, when the buffer chamber is viewed in the direction of the central axis, the inner wall surface of the buffer chamber extends from the inlet of the buffer chamber to which the upstream flow path section is connected in a direction along the connection direction in which the upstream flow path section connects to the buffer chamber, and includes a side wall surface located on the side of the inlet of the measurement flow path section, and the guide wall section may include a side guide wall section protruding from the side wall surface toward the inlet of the measurement flow path section. According to the gas meter of the fifth aspect, a portion of the gas flowing along the side wall surface in the buffer chamber can be guided to the inlet of the measurement flow path section by the side guide wall section, thereby making the flow of gas from the buffer chamber to the inlet of the measurement flow path section even smoother.

[0012] [Sixth Form] In the gas meter described in any one of the first, second, third, fourth and fifth forms, the inner wall surface of the buffer chamber includes a rear wall surface that is located opposite the inlet of the buffer chamber to which the upstream flow path section is connected, across the inlet of the measurement flow path section, when the buffer chamber is viewed in the central axis direction, and the guide wall section may include a rear guide wall section that protrudes from the rear wall surface toward the inlet of the measurement flow path section. According to the gas meter of the sixth aspect, a portion of the gas flowing along the inner wall surface in the buffer chamber can be guided to the inlet of the measurement flow path by the inner guide wall, thereby further smoothing the flow of gas flowing from the buffer chamber to the inlet of the measurement flow path.

[0013] [Seventh Mode] In the gas meter described in any one of the first, second, third, fourth, fifth, and sixth modes, when the buffer chamber is viewed in the central axis direction, the inner wall surface of the buffer chamber extends from the inlet of the buffer chamber to which the upstream flow path section is connected in a direction along the connection direction in which the upstream flow path section connects to the buffer chamber, and includes a side wall surface located on either side of the inlet of the measurement flow path section, and an opposite side wall surface facing the side wall surface across the inlet of the measurement flow path section, and the guide wall portion may include an opposite side guide wall portion protruding from the opposite side wall surface toward the inlet of the measurement flow path section. According to the gas meter of the seventh aspect, a portion of the gas flowing along the opposite side wall surface in the buffer chamber can be guided to the inlet of the measurement flow path section by the opposite side guide wall section, thereby further smoothing the flow of gas flowing from the buffer chamber to the inlet of the measurement flow path section.

[0014] [Eighth Mode] In the gas meter according to any one of the first, second, third, fourth, fifth, sixth, and seventh modes, when the buffer chamber is viewed in the direction of the central axis, the inner wall surface of the buffer chamber extends from the inlet of the buffer chamber in a direction along the connection direction in which the upstream flow path section connects to the buffer chamber, and includes a side wall surface located on either side of the inlet of the measurement flow path section, and a rear wall surface located opposite the inlet of the buffer chamber across the inlet of the measurement flow path section, and the guide wall portion may include an inlet guide wall portion that protrudes at the inlet of the buffer chamber connected to the upstream flow path section so as to face the outlet of the upstream flow path section, a side guide wall portion that protrudes from the side wall surface toward the inlet of the measurement flow path section, and a rear guide wall portion that protrudes from the rear wall surface toward the inlet of the measurement flow path section. According to the gas meter of the eighth aspect, a portion of the gas flowing in from the inlet of the buffer chamber can be guided to the inlet of the measurement flow path section by the inlet guide wall section, and a portion of the gas flowing in a direction along the side wall surface of the buffer chamber can be guided to the inlet of the measurement flow path section by the side guide wall section. Furthermore, a portion of the gas flowing in a direction along the inner wall surface of the buffer chamber can be guided to the inlet of the measurement flow path section by the inner guide wall section. Therefore, gas flowing into the buffer chamber from the upstream flow path section can be guided more smoothly to the inlet of the measurement flow path section, thereby further reducing gas pressure loss in the gas meter.

[0015] [Configuration 9] In the gas meter described in Configuration 8 above, the inner wall surface of the buffer chamber may further include an opposite side wall surface that faces the side wall surface across the inlet of the measurement flow path section when the buffer chamber is viewed in the central axis direction, and the guide flow path may further include an opposite side guide wall portion that protrudes from the opposite side wall surface toward the inlet of the measurement flow path section. According to the gas meter of the ninth embodiment, furthermore, a portion of the gas flowing along the opposite side wall surface can be guided to the inlet of the measurement flow path section by the opposite side guide wall section, thereby further smoothing the flow of gas flowing into the inlet of the measurement flow path section.

[0016] The technology of the present disclosure can also be realized in various forms other than a gas meter, such as a measurement unit housed in a gas meter and measuring the gas flow rate, a main body of the gas meter housing the measurement unit, a gas flow path structure in a gas meter or a measurement unit, a housing member in which a gas flow path is formed in a gas meter or a measurement unit, a gas supply system including a gas meter, etc. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic perspective view showing the external configuration of a gas meter. [Figure 2] FIG. 2 is a schematic exploded perspective view showing the internal configuration of a gas meter. [Figure 3]FIG. 3 is a schematic perspective view showing the rear side of the support member in the first embodiment. [Figure 4] FIG. 3 is a schematic perspective view showing the front side of the support member in the first embodiment. [Figure 5] FIG. 2 is a schematic perspective view showing a support structure according to the first embodiment. [Figure 6] FIG. 2 is a schematic cross-sectional view showing the support structure of the first embodiment. [Figure 7] Schematic diagram showing the mechanism of engagement of the seismic sensor with a pair of columnar portions. [Figure 8] FIG. 10 is a schematic perspective view showing a support member according to a second embodiment. [Figure 9] FIG. 10 is a schematic diagram showing a list of inlet buffer chambers in other configuration examples. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1. First embodiment: 1-1.Outline of gas meter configuration: The schematic configuration of a gas meter 10 of the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic perspective view showing the external configuration of the gas meter 10. Figure 2 is a schematic exploded perspective view of a main body 11 of the gas meter 10.

[0019] 1 and 2 show arrows indicating three mutually orthogonal directions X, Y, and Z. The X direction corresponds to the width direction of the gas meter 10, i.e., the left-right direction. The Y direction corresponds to the depth direction of the gas meter 10, i.e., the front-to-back direction. The Z direction corresponds to the height direction of the gas meter 10, i.e., the up-to-down direction. The above terms "left," "right," "front," "rear," "up," and "down" basically correspond to the directions when facing the gas meter 10 in its normal usage position properly attached to a gas pipe. When the gas meter 10 is in its normal usage position, the Z direction is along the direction of gravity, and the X and Y directions are along the horizontal direction. The X direction is from right to left, the Y direction is from front to rear, and the Z direction is from bottom to top. The arrows indicating the three directions X, Y, and Z are also appropriately illustrated in each figure referred to later so as to correspond to FIG. 1.

[0020] The gas meter 10 is an ultrasonic gas meter that uses ultrasonic waves to measure the flow rate of a gas to be measured. The gas meter 10 is connected to a gas pipe (not shown) and measures the flow rate of the gas flowing through the gas pipe. The gas pipe corresponds to a supply source that supplies gas to the gas meter 10. The pressure of the gas supplied from the gas pipe to the gas meter 10 may be, for example, 0.5 KPa or more and 4.0 KPa or less.

[0021] Referring to Figure 1, the gas meter 10 includes a main body 11 having a substantially rectangular parallelepiped shape. The top surface of the main body 11 is provided with a gas inlet 12 into which gas flows and a gas outlet 13 from which gas flows out. The gas inlet 12 and the gas outlet 13 are each configured as cylindrical portions that protrude upward from the top surface of the main body 11, and can be connected to gas pipes. The gas inlet 12 is provided at the left end of the top surface of the main body 11, and the gas inlet 12 is provided at the right end of the top surface of the main body 11.

[0022] A recess 14 is formed on the front surface of the main body 11 for mounting a shutoff valve 15, which will be described later. Although not shown for convenience, a front panel is usually attached to the front surface of the gas meter 10, and the recess 14 is covered by the front panel. The front panel is provided with a display unit that displays information such as measurement results, status information, and messages, an operation unit that accepts operations by an operator, and the like. A detailed description of the front panel unit will be omitted for convenience.

[0023] 2, the main body 11 includes an exterior part 20, a bottom wall part 21, and a measurement unit 23.

[0024] The exterior part 20 is made up of a member having a substantially rectangular parallelepiped shape and forms the outer shell of the main body part 11. The exterior part 20 has the gas inlet part 12 and the gas outlet part 13 described above on its top surface, and has a recess 14 that houses the shut-off valve 15 described above on its front surface. The exterior part 20 has an internal space that can house the internal components of the gas meter 10, such as the measurement unit 23, a circuit board (not shown), and a power supply part. A gas flow path, which will be described later, is also formed inside the exterior part 20. The entire bottom side of the exterior part 20 is open so that internal components, such as the measurement unit 23, can be inserted from below.

[0025] The bottom wall 21 is made of a plate-like member having a substantially rectangular shape. The bottom wall 21 is attached so as to close the opening at the bottom of the exterior part 20, and constitutes the bottom surface of the main body part 11. The bottom wall 21 is fixed to the exterior part 20 by, for example, screws. The measurement unit 23 is housed inside the exterior part 20 while being placed on the upper surface of the bottom wall 21.

[0026] The measurement unit 23 is a component that measures the flow rate of gas and includes a measurement flow path section 25, a flow meter side section 26, an upper case section 27a, and a lower case section 27b.

[0027] The measurement flow path section 25 is configured by a tubular member through which gas flows. Both ends of the measurement flow path section 25 are open and function as a gas inlet 25i and an outlet 25o, respectively. In the first embodiment, the measurement flow path section 25 has a substantially rectangular prism shape and is disposed horizontally along the X direction within the gas meter 10.

[0028] 2 shows the central axis CX of measurement flow path section 25. In the first embodiment, measurement flow path section 25 has a configuration that extends linearly, and central axis CX of measurement flow path section 25 corresponds to the central axis of inlet 25i of measurement flow path section 25. Central axis CX of measurement flow path section 25 is similarly shown in other figures to be referred to later.

[0029] The flow meter side section 26 is equipped with an ultrasonic sensor, and irradiates ultrasonic waves onto the gas flowing through the measurement flow path section 25 to output a signal representing the flow rate of the gas. The flow meter side section 26 is attached to the upper surface of the measurement flow path section 25. The method of measuring the gas flow rate by the flow meter side section 26 will be described later.

[0030] The upper housing part 27a and the lower housing part 27b are fitted together vertically to form the outer shell of the measurement unit 23. The measurement flow path part 25 and the flow meter side part 26 are housed in an internal space formed between the upper housing part 27a and the lower housing part 27b.

[0031] Two buffer chambers 30, 40, which are airtight spaces that respectively accommodate inlet 25i and outlet 25o of measurement flow path section 25, are defined between upper housing section 27a and lower housing section 27b. Inlet 25i of measurement flow path section 25 is arranged in inlet buffer chamber 30. Outlet 25o of measurement flow path section 25 is arranged in outlet buffer chamber 40. Inlet buffer chamber 30 of the first embodiment is formed with a guide wall section 35 for facilitating the flow of gas into inlet 25i of measurement flow path section 25. Guide wall section 35 will be described later.

[0032] 1-2. Internal structure of a gas meter: The internal structure of the gas meter 10 will be described with appropriate reference to Figures 3 to 5. Figure 3 is a schematic cross-sectional view of the gas meter 10 taken along line 3-3 in Figure 1. Figure 4 is a schematic cross-sectional view of the gas meter 10 taken along line 4-4 in Figure 3. Figure 5 is a schematic cross-sectional view of the inlet buffer chamber 30 and the measurement flow path section 25 taken along line 5-5 in Figure 4.

[0033] 1-2-1. Overview of the internal structure of a gas meter: An outline of the internal configuration of the gas meter will be described with reference to Fig. 3. The above-mentioned measurement unit 23 is disposed in a lower region inside the main body 11 of the gas meter 10. In an upper region inside the main body 11, an inlet gas flow path 31 communicating with the gas inlet portion 12 and an outlet gas flow path 41 communicating with the gas outlet portion 13 are formed.

[0034] Below the inlet gas flow path 31, there are formed a valve chamber 32 that houses the valve element 16 of the shutoff valve 15, and an upstream flow path section 33. The inlet gas flow path 31 is in communication with the valve chamber 32, and the valve chamber 32 is in communication with the upstream flow path section 33. Below the upstream flow path section 33, there is disposed an inlet buffer chamber 30 of the measurement unit 23. The upstream flow path section 33 is in communication with the inlet buffer chamber 30. Below the outlet gas flow path 41, there is disposed an outlet buffer chamber 40 of the measurement unit 23. The outlet gas flow path 41 is in communication with the outlet buffer chamber 40.

[0035] As described above, the measurement flow path section 25 of the measurement unit is disposed horizontally along the X direction within the gas meter 10. Therefore, in the first embodiment, the direction of the central axis CX of the measurement flow path section 25 coincides with the X direction. The inlet 25i of the measurement flow path section 25 is disposed in the inlet buffer chamber 30, and the outlet 25o of the measurement flow path section 25 is disposed in the outlet buffer chamber 40. The flow meter side section 26 is attached above the measurement flow path section 25 and is disposed in the center of the gas meter 10 in the width direction.

[0036] 1-2-2. Gas flow within the gas meter: Referring to Figure 3, in gas meter 10, gas that has flowed into gas inlet section 12 from an external gas pipe flows through inlet gas flow path 31 to valve chamber 32, and then flows from valve chamber 32 through upstream flow path section 33 into inlet buffer chamber 30. Inlet buffer chamber 30 receives the gas flowing in from upstream flow path section 33 and functions to buffer the impact of gas pressure when the gas flows out from upstream flow path section 33.

[0037] Gas that flows into inlet buffer chamber 30 flows into measurement flow path section 25, passes through measurement flow path section 25, and flows into outlet buffer chamber 40. Outlet buffer chamber 40 has the function of receiving the gas that flows in from measurement flow path section 25 and mitigating the impact of the gas pressure when the gas flows out from measurement flow path section 25. The gas that flows into outlet buffer chamber 40 flows through outlet gas flow path 41 to gas outflow section 13, and then flows through gas outflow section 13 to an external gas pipe.

[0038] 1-2-3.Gas flow measurement: The flowmeter side unit 26 transmits ultrasonic waves UW, indicated by dashed arrows, into the measurement flow path unit 25 through which the gas flows, and receives the ultrasonic waves UW reflected by the inner wall surface of the measurement flow path unit 25. The flowmeter side unit 26 measures the time required from transmission to reception of the ultrasonic waves UW, and calculates the gas flow rate based on the measured time. Although not shown in the figures or described in detail, the flowmeter side unit 26 outputs a signal representing the gas flow rate to a microcomputer housed in the gas meter 10 and functioning as a control unit of the gas meter 10.

[0039] To improve the accuracy of measuring the gas flow rate by flowmeter section 26, it is preferable that the gas flow be stable within measurement flow path section 25. In measurement flow path section 25 of the first embodiment, the internal gas flow path is configured to be linear, and the flow path cross section is configured to be approximately uniform. Therefore, measurement flow path section 25 of the first embodiment prevents turbulence in the gas within measurement flow path section 25 and prevents bias in the gas flow velocity distribution, thereby improving the accuracy of measuring the gas flow rate.

[0040] In the first embodiment, both ends of measurement flow path section 25 have a tapered shape with an opening area that increases toward the ends. This configuration facilitates the flow of gas into inlet 25i of measurement flow path section 25 and the flow of gas out from outlet 25o of measurement flow path section 25, thereby suppressing the generation of gas turbulence within measurement flow path section 25 and the increase in gas pressure loss in measurement flow path section 25.

[0041] 1-2-4. Configuration of the gas flow path on the inlet side and details of the gas flow: See Figure 4. The valve chest 32 and the upstream flow path section 33, which constitute the gas flow path on the inlet side of the gas meter 10, are provided above the inlet buffer chamber 30, and the upstream flow path section 33 is located rearward of the valve chest 32. The valve chest 32 opens rearward and communicates with the upstream flow path section 33. The upstream flow path section 33 extends downward and is connected to the inlet buffer chamber 30 from above.

[0042] The upstream flow path section 33 is connected from above the inlet buffer chamber 30 to a rear end region of the inlet buffer chamber 30 that is shifted rearward from the central axis CX of the measurement flow path section 25. In other words, when the inlet buffer chamber 30 is viewed in the direction of the central axis CX of the measurement flow path section 25, the upstream flow path section 33 is connected to an end region of the inlet buffer chamber 30 that is shifted from the central axis CX from a direction perpendicular to the central axis CX. The reason why the upstream flow path section 33 is connected to the inlet buffer chamber 30 in this manner will be described later.

[0043] The gas that flows in from the gas inlet section 12 flows downward from the inlet gas flow path 31 to the valve chamber 32, and then the flow direction is bent backward in the valve chamber 32 and flows into the upstream flow path section 33. Furthermore, the flow direction of the gas is bent downward again in the upstream flow path section 33 and flows into the inlet buffer chamber 30. In this way, in the gas meter 10, the gas flow is bent twice in a crank shape just before the inlet buffer chamber 30. This flow path configuration suppresses the generation of turbulent gas flow in the measurement flow path section 25.

[0044] As described above, the valve chamber 32 accommodates the valve element 16 of the shutoff valve 15. In normal use, the valve element 16 of the shutoff valve 15 is located away from the inlet of the upstream flow path section 33, and opens the inlet of the upstream flow path section 33. In the gas meter 10, when a built-in sensor or the like detects vibrations due to an earthquake or the like, or when the gas meter 10 receives a valve closing operation from an operator, the shutoff valve 15 is actuated and the valve element 16 closes the inlet of the upstream flow path section 33.

[0045] In the gas meter 10, the valve chamber 32 communicates with the recess 14 on the front surface of the exterior part 20, and the shutoff valve 15 can be attached by inserting it through the opening of the recess 14 provided on the front surface of the main body part 11. Therefore, according to the gas meter 10 of the first embodiment, the shutoff valve 15 can be easily attached to and detached from the main body part 11.

[0046] 3. In gas meter 10, inlet end portion 25t having inlet 25i of measurement flow path portion 25 protrudes in the X direction into inlet buffer chamber 30. In the first embodiment, inlet 25i of measurement flow path portion 25 is located closer to the inner wall surface on the X direction side than the center in the X direction of inlet buffer chamber 30. In other words, the distance between inlet 25i of measurement flow path portion 25 and the inner wall surface of inlet buffer chamber 30 facing the inlet is shorter than the length of inlet end portion 25t of measurement flow path portion 25 protruding into inlet buffer chamber 30.

[0047] In the first embodiment, inlet buffer chamber 30 has upper wall portion 34 that protrudes in the direction opposite to the X direction from the inner wall surface facing inlet 25i of measurement flow path section 25, and inlet 30i of inlet buffer chamber 30 opens above inlet end portion 25t of measurement flow path section 25. Upper wall portion 34 is formed so as not to overlap with measurement flow path section 25 in the Z direction to prevent an increase in gas pressure loss.

[0048] 4. In the first embodiment, when the inlet buffer chamber 30 is viewed in the direction of the central axis CX, the inlet 25i of the measurement flow path section 25 is disposed at a position spaced apart from each of the inner wall surfaces 51, 52, and 53 of the inlet buffer chamber 30 that surround the inlet 25i of the measurement flow path section 25. More specifically, the inlet 25i of the measurement flow path section 25 is disposed near the center of the inlet buffer chamber 30.

[0049] 1-2-5.Configuration of the guide wall of the entrance buffer room: 4, inlet buffer chamber 30 is provided with guide wall portions 35 for smoothly guiding gas that has flowed into inlet buffer chamber 30 from upstream flow path section 33 to inlet 25i of measurement flow path section 25. In the first embodiment, multiple guide wall portions 35 are formed around inlet 25i of measurement flow path section 25. When inlet buffer chamber 30 is viewed in the direction of central axis CX, guide wall portions 35 are formed so as not to interfere with inlet 25i of measurement flow path section 25, and protrude from inner wall surfaces 51, 52, and 53 of inlet buffer chamber 30 that are located around inlet 25i of measurement flow path section 25 in an area outside inlet 25i of measurement flow path section 25.

[0050] Before describing the guide wall portion 35 in detail, we will explain the inner wall surfaces 51, 52, and 53 of the inlet buffer chamber 30 on which the guide wall portion 35 is formed. As shown in Fig. 4, the inlet buffer chamber 30 has three inner wall surfaces 51, 52, and 53 around the central axis CX.

[0051] The first inner wall surface 51 is one of the side wall surfaces of the inlet buffer chamber 30, and is located on the back side of the gas meter 10. The first inner wall surface 51 is located below the outlet of the upstream flow path section 33. The first inner wall surface 51 extends downward from the inlet 30i of the inlet buffer chamber 30, to which the upstream flow path section 33 is connected, in the connection direction of the upstream flow path section 33 to the inlet buffer chamber 30, and is located to the side of the measurement flow path section 25. Hereinafter, the first inner wall surface 51 will also be referred to as the "side wall surface 51."

[0052] The second inner wall surface 52 corresponds to the bottom surface of the inlet buffer chamber 30, and is located on the bottom side of the gas meter 10. The second inner wall surface 52 is located opposite the inlet 30i of the inlet buffer chamber 30, across the inlet 25i of the measurement flow path section 25, and is located at the back of the inlet buffer chamber 30 when viewed from the inlet 30i of the inlet buffer chamber 30. Hereinafter, the second inner wall surface 52 will also be referred to as the "rear wall surface 52."

[0053] The third inner wall surface 53 is one of the side wall surfaces of the inlet buffer chamber 30, and is located on the front side of the gas meter 10. The third inner wall surface 53 faces the side wall surface 51 across the inlet 25i of the measurement flow path section 25. Hereinafter, the third inner wall surface 53 will also be referred to as the "opposite side wall surface 53."

[0054] The guide wall portion 35 of the first embodiment includes an entrance guide wall portion 35a, a side guide wall portion 35b, a rear guide wall portion 35c, and an opposite side guide wall portion 35d.

[0055] The inlet guide wall portion 35a is provided at the inlet 30i of the inlet buffer chamber 30. The inlet guide wall portion 35a protrudes so as to face the outlet of the upstream flow path portion 33. In the first embodiment, the inlet guide wall portion 35a is provided above the measurement flow path portion 25, and extends in the X direction from the upper end of the side wall surface 51.

[0056] Inlet guide wall portion 35a protrudes to a position where it does not overlap with measurement flow path portion 25 when viewed along the Z direction. In the first embodiment, inlet guide wall portion 35a has a height that is 50% to 95% of distance Da between side wall surface 51 and the side surface of measurement flow path portion 25. It is preferable that inlet guide wall portion 35a has a height that is 60% to 90% of distance Da.

[0057] The lateral guide wall portion 35b protrudes from the lateral wall surface 51 toward the inlet 25i of the measurement flow path portion 25. In the first embodiment, the lateral guide wall portion 35b extends from the lateral wall surface 51 toward the inlet 25i of the measurement flow path portion 25 on the side of the measurement flow path portion 25. In addition, in the first embodiment, the lateral guide wall portion 35b extends horizontally from the lateral wall surface 51 at the center of the lateral wall surface 51 in the Z direction.

[0058] When viewed in the direction of the central axis CX, a gap is formed between the side guide wall portion 35b and the side surface of the measurement flow path portion 25. In the first embodiment, the side guide wall portion 35b has a height that is 50% to 95% of the distance Da, similar to the inlet guide wall portion 35a. It is preferable that the side guide wall portion 35b has a height that is 60% to 90% of the distance Da.

[0059] The rear guide wall portion 35c protrudes from the rear wall surface 52 toward the inlet 25i of the measurement flow path portion 25. In the first embodiment, the rear guide wall portion 35c extends from the rear wall surface 52 toward the inlet 25i of the measurement flow path portion 25 below the measurement flow path portion 25. In the first embodiment, the side guide wall portion 35b extends vertically upward from the rear wall surface 52 at the center of the rear wall surface 52 in the Y direction.

[0060] When viewed in the direction of the central axis CX, the depth guide wall portion 35c is formed with a height such that the tip of the depth guide wall portion 35c is located closer to the depth wall surface 52 than the inlet 25i of the measurement flow path portion 25. In the first embodiment, the depth guide wall portion 35c has a height that is 10% to 50% of the distance Db between the depth wall surface 52 and the side surface of the measurement flow path portion 25. It is preferable that the depth guide wall portion 35c has a height that is 15% to 40% of the distance Db.

[0061] Opposite side guide wall 35d protrudes from opposite side wall surface 53 toward inlet 25i of measurement flow path section 25. In the first embodiment, opposite side guide wall 35d extends from opposite side wall surface 53 toward inlet 25i of measurement flow path section 25 on the side of measurement flow path section 25. Also, in the first embodiment, opposite side guide wall 35d extends horizontally from opposite side wall surface 53 at the center of opposite side wall surface 53 in the Z direction.

[0062] When viewed in the direction of the central axis CX, a gap is formed between opposite side guide wall portion 35d and the side surface of measurement flow path portion 25. In the first embodiment, opposite side guide wall portion 35d has a height that is 50% to 95% of the distance Dc between opposite side wall surface 53 and the side surface of measurement flow path portion 25. It is preferable that opposite side guide wall portion 35d has a height that is 60% to 90% of the distance Dc.

[0063] See Figures 3 and 5. When viewed from a direction perpendicular to the central axis CX, each guide wall 35 has a portion that extends toward the inlet 25i of the measurement flow path section 25 in a region forward of the inlet 25i of the measurement flow path section 25 of the inlet buffer chamber 30. It is preferable that the guide wall 35 extends from a region forward of the inlet 25i of the measurement flow path section 25 to a region rearward. In the first embodiment, the guide wall 35 extends from one end of the inlet buffer chamber 30 to the other end of the central axis CX.

[0064] 1-2-6.Function of the guide wall: The function of the above-mentioned guide wall portion 35 will be described with reference to FIGS.

[0065] 6 is a schematic diagram of the inlet buffer chamber 30a of the gas meter 10cf of the reference example when viewed in the direction of the central axis CX. The configuration of the gas meter 10cf of the reference example is substantially the same as the configuration of the gas meter 10 of the first embodiment, except that the gas meter 10cf of the reference example has an inlet buffer chamber 30cf without the guide wall portion 35. In FIG. 6, the position where the guide wall portion 35 of the first embodiment is formed is shown by a dashed line to show the correspondence with the configuration of the first embodiment.

[0066] In gas meter 10cf of the reference example, similarly to gas meter 10 of the first embodiment, upstream flow path section 33 is connected from a direction perpendicular to the direction of central axis CX to an end region of inlet buffer chamber 30cf that is shifted from central axis CX when inlet buffer chamber 30cf is viewed in the direction of central axis CX of measurement flow path section 25. As a result, in inlet buffer chamber 30cf of the reference example, gas that has flowed in from upstream flow path section 33 flows into inlet 25i of measurement flow path section 25 while swirling in a spiral shape around central axis CX of measurement flow path section 25, as shown by arrow SP.

[0067] FIG. 7 is a schematic diagram of the inlet buffer chamber 30 of the gas meter 10 of the first embodiment when viewed in the direction of the central axis CX.

[0068] In the gas meter 10 of the first embodiment, like the gas meter 10cf of the reference example described above, the upstream flow path portion 33 is connected to the inlet buffer chamber 30 in such a way that, without the guide wall portion 35, a spiral gas flow would be formed in the inlet buffer chamber 30. However, in the inlet buffer chamber 30 of the first embodiment, the guide wall portion 35 is formed, so that the gas that flows in from the upstream flow path portion 33 flows as follows.

[0069] In gas meter 10 of the first embodiment, when gas flows in from upstream flow path section 33, inlet guide wall section 35a forms a gas flow that flows from inlet 30i of inlet buffer chamber 30 toward inlet 25i of measurement flow path section 25, as shown by arrow Fa. Furthermore, gas that passes over inlet guide wall section 35a and flows toward side wall surface 51 and flows along side wall surface 51 is guided by side guide wall section 35b to inlet 25i of measurement flow path section 25, as shown by arrow Fb. Gas that passes over side guide wall section 35b flows along side wall surface 51 and rear wall surface 52, as shown by arrow Fc, and is guided by rear guide wall section 35c to inlet 25i of measurement flow path section 25.

[0070] A portion of the gas that is guided by inlet guide wall portion 35a and flows toward opposite side wall surface 53 and flows along opposite side wall surface 53 is guided by opposite side wall surface 53 to inlet 25i of measurement flow path portion 25, as shown by arrow Fd. Furthermore, the gas that has passed over opposite side guide wall portion 35d flows along opposite side wall surface 53 and rear wall surface 52, as shown by arrow Fe, and is guided by rear guide wall portion 35c to inlet 25i of measurement flow path portion 25.

[0071] In inlet buffer chamber 30cf of the reference example shown in Fig. 6, the gas flow from the inlet of inlet buffer chamber 30cf to inlet 25i of measurement flow path section 25 becomes a large spiral flow, increasing the gas path length and correspondingly increasing gas pressure loss. In contrast, inlet buffer chamber 30 of the first embodiment shown in Fig. 7, guide wall section 35 forms multiple gas paths toward inlet 25i of measurement flow path section 25, and is configured to efficiently collect gas at inlet 25i of measurement flow path section 25. This more smoothly allows gas to flow into inlet 25i of measurement flow path section 25, reducing gas pressure loss.

[0072] In gas meter 10 of the first embodiment, as shown in FIGS. 3 and 5 , each guide wall 35 extends from a region in front of inlet 25i of measurement flow path section 25 to a region behind inlet 25i of measurement flow path section 25 when viewed in a direction perpendicular to central axis CX. This makes it easier for each guide wall 35 to guide gas around the inlet of the measurement flow path section to inlet 25i of measurement flow path section 25. This further reduces pressure loss of gas when it flows into inlet 25i of measurement flow path section 25. In gas meter 10 of the first embodiment, each guide wall 35 is formed across the entire inlet buffer chamber 30 in the direction of central axis CX, making it even easier for gas to be guided to inlet 25i of measurement flow path section 25.

[0073] Furthermore, according to experiments conducted by the inventors of the present invention, it has been confirmed that the gas pressure loss in the configuration of the gas meter 10 of the first embodiment is reduced to approximately 80% of the gas pressure loss in the configuration of the gas meter 10cf of the reference example.

[0074] 1-3. Summary of the first embodiment: As described above, according to gas meter 10 of the first embodiment, inlet buffer chamber 30 is formed with guide wall portion 35, including inlet guide wall portion 35a, side guide wall portion 35b, rear guide wall portion 35c, and opposite-side guide wall portion 35. This facilitates the flow of gas into inlet 25i of measurement flow path portion 25, and reduces pressure loss of gas when it flows into inlet 25i of measurement flow path portion 25.

[0075] 2. Second embodiment: 8 is a schematic cross-sectional view showing the configuration of the inlet buffer chamber 30A included in the gas meter 10A of the second embodiment. The configuration of the gas meter 10A of the second embodiment is substantially the same as the configuration of the gas meter 10 of the second embodiment, except that the opposite side guide wall portion 35d is not provided in the inlet buffer chamber 30A.

[0076] Even if opposite side guide wall 35d is not provided, gas that is guided by inlet guide wall 35a and flows toward opposite side wall surface 53 flows along opposite side wall surface 53 while flowing into inlet 25i of measurement flow path section 25, as shown by arrow Ff. Furthermore, gas that passes along opposite side wall surface 53 to the side of inlet 25i of measurement flow path section 25 flows along back wall surface 52, and is guided by back guide wall 35c to inlet 25i of measurement flow path section 25, as shown by arrow Fg.

[0077] According to the gas meter 10A of the second embodiment, similarly to the gas meter 10 of the first embodiment, it is possible to allow the gas in the inlet buffer chamber 30A to smoothly flow into the inlet 25i of the measurement flow path section 25. Therefore, it is possible to reduce the pressure loss of the gas when it flows into the measurement flow path section 25. In addition, according to the gas meter 10A of the second embodiment, it is possible to achieve various operational effects similar to those described in the first embodiment.

[0078] 3.Other configuration examples: Other configuration examples of inlet buffer chambers 30a, 30b, 30c, and 30d will be described with reference to Fig. 9. Columns (a), (b), (c), and (d) of Fig. 9 each illustrate configuration examples of a plurality of inlet buffer chambers 30a, 30b, 30c, and 30d having different configurations of the guide wall portion 35. In the configuration examples described below, the configuration of the gas meter is substantially the same as that described in the first embodiment above, except for the inlet buffer chambers 30a, 30b, 30c, and 30d.

[0079] 9(a) shows inlet buffer chamber 30a of a first configuration example, which is provided with only one inlet guide wall portion 35a similar to that described in the first embodiment as guide wall portion 35. Even with this configuration, inlet guide wall portion 35a can form a gas flow that flows from inlet 30i of inlet buffer chamber 30 to inlet 25i of measurement flow path portion 25, as shown by arrow Fa in FIGS.

[0080] 9(b), inlet buffer chamber 30b of the second configuration example is provided with only one side guide wall portion 35b similar to that described in the first embodiment as guide wall portion 35. Even with this configuration, side guide wall portion 35b can form a gas flow that directs a portion of the gas flowing along side wall surface 51 toward inlet 25i of measurement flow path portion 25, as shown by arrow Fb in FIGS.

[0081] 9(c) shows inlet buffer chamber 30c of a third configuration example, which is provided with only one rear guide wall portion 35c similar to that described in the first embodiment as guide wall portion 35. Even with this configuration, rear guide wall portion 35c can form a gas flow that directs a portion of the gas flowing along rear wall surface 52 toward inlet 25i of measurement flow path portion 25, as shown by arrows Fc, Fe, and Fg in FIGS.

[0082] 9(d) shows inlet buffer chamber 30d of a fourth configuration example, in which only one opposite side guide wall portion 35d similar to that described in the first embodiment is provided as guide wall portion 35. Even with this configuration, opposite side guide wall portion 35d can form a gas flow that directs a portion of the gas flowing along opposite side wall surface 53 toward inlet 25i of measurement flow path portion 25, as shown by arrow Fd in FIG.

[0083] As described above, if at least one guide wall portion 35 is provided, it is possible to facilitate the flow of gas into inlet 25i of measurement flow path portion 25, and to reduce the pressure loss of the gas when it flows into inlet 25i of measurement flow path portion 25. Furthermore, by appropriately combining two or more guide walls 35a, 35b, 35c, 35d, it is possible to further facilitate the flow of gas into inlet 25i of measurement flow path portion 25, and to further reduce the pressure loss of the gas when it flows into inlet 25i of measurement flow path portion 25.

[0084] 4. Other embodiments: The technology of the present disclosure is not limited to the configurations described in the above-described embodiments or other configuration examples, and may be modified, for example, as described below. Note that, in this specification, all configurations described as other embodiments are positioned as examples of modes for implementing the technology of the present disclosure, similar to the above-described embodiments and other configuration examples.

[0085] 6-1. Other embodiment 1: The number of guide walls 35 is not limited to the numbers described in the above embodiments and other configuration examples. For example, multiple side guide walls 35b may be provided on side wall surface 51. Similarly, multiple rear guide walls 35c and opposite side guide walls 35d may be provided on rear wall surface 52 and opposite side wall surface 53, respectively. Furthermore, side guide walls 35b do not have to protrude perpendicularly to side wall surface 51 and may, for example, protrude obliquely from side wall surface 51. Similarly, inlet guide wall 35a, rear guide wall 35c, and opposite side guide wall 35d may protrude obliquely from side wall surface 51, rear wall surface 52, and opposite side wall surface 53, respectively. It is sufficient that guide wall 35 has a portion extending at least in a region forward of inlet 25i of measurement flow path section 25 in the direction of central axis CX. Guide wall portion 35 does not necessarily have to have a portion that extends rearward of inlet 25i of measurement flow path portion 25 in the direction of central axis CX.

[0086] 6-2. Alternative embodiment 2: The configuration of the gas flow path in the gas meter is not limited to the configurations described in the above embodiments. For example, in the configuration of the above first embodiment, the upstream flow path section 33 may be configured to be connected to the upper end of the inlet buffer chamber 30 from the rear side. Furthermore, the upstream flow path section 33 may be connected to the valve chamber 32 from the side or below.

[0087] 6-3. Other embodiment 3: In the above-described embodiments and other configuration examples, the gas flow path in the gas meter is configured so that, when guide wall portion 35 is omitted, a spiral gas flow is formed centered on inlet 25i of measurement flow path portion 25. However, the gas flow path in the gas meter does not have to be configured so that, when guide wall portion 35 is omitted, a spiral gas flow is formed centered on inlet 25i of measurement flow path portion 25. Even in such cases, as long as at least one guide wall portion 35 is provided, a gas flow toward inlet 25i of measurement flow path portion 25 is formed in inlet buffer chamber 30, 30A, 30a, 30b, 30c, 30d, thereby making it possible to reduce gas pressure loss. [Explanation of symbols]

[0088] 10, 10A, 10cf...gas meter, 11...main body, 12...gas inlet, 13...gas outlet, 14...recess, 15...shutoff valve, 16...valve body, 20...exterior, 21...bottom wall, 23...measuring unit, 25...measuring flow path, 25i...inlet, 25o...outlet, 25t...inlet end, 26...flow meter side, 27a...upper housing, 27b...lower housing, 30, 30A, 30a, 30b, 30c, 30d, 30cf...inlet buffer chamber, 30i...inlet, 31...inlet gas flow path , 32... valve chamber, 33... upstream flow path portion, 34... upper wall portion, 35... guide wall portion, 35a... inlet guide wall portion, 35b... side guide wall portion, 35c... rear guide wall portion, 35d... opposite side guide wall portion, 40... outlet buffer chamber, 41... outlet gas flow path, 51... side wall surface (first inner wall surface), 52... rear wall surface (second inner wall surface), 53... opposite side wall surface (third inner wall surface), CX... central axis, UW... ultrasonic wave, SP... spiral gas flow, Fa, Fb, Fc, Fd, Fe, Ff... gas flow

Claims

1. A gas meter, a tubular measurement flow path portion through which a gas to be measured flows; a flow rate measuring unit that measures the flow rate of the gas flowing through the measurement flow path unit by irradiating an ultrasonic wave into the measurement flow path unit; a buffer chamber in which an inlet of the measurement flow path section is disposed and which guides the gas to the inlet of the measurement flow path section; an upstream flow path section that configures a flow path that guides the gas to the buffer chamber, and that is connected to an end region of the buffer chamber that is shifted from the central axis when the buffer chamber is viewed in the direction of the central axis of the inlet of the measurement flow path section, in a direction perpendicular to the central axis direction; at least one guide wall portion that protrudes from an inner wall surface of the buffer chamber around the inlet of the measurement flow path portion in an area outside the inlet of the measurement flow path portion when the buffer chamber is viewed in the direction of the central axis, and has a portion that extends toward the inlet side of the measurement flow path portion in an area in front of the inlet of the measurement flow path portion when viewed in a direction perpendicular to the direction of the central axis; A gas meter comprising:

2. 2. The gas meter according to claim 1, A gas meter, wherein a plurality of the guide walls are formed around an inlet of the measurement flow path portion when the buffer chamber is viewed in the central axis direction.

3. A gas meter according to claim 1, an inlet of the measurement flow path portion is disposed at a position protruding from an inner wall surface of the buffer chamber in the direction of the central axis, The gas meter, wherein the guide wall portion extends from a region in front of an inlet of the measurement flow path portion to a region behind the inlet when viewed in a direction perpendicular to the central axis direction.

4. The gas meter according to any one of claims 1 to 3, The gas meter, wherein the guide wall portion includes an inlet guide wall portion that protrudes at an inlet of the buffer chamber to which the upstream flow path portion is connected so as to face an outlet of the upstream flow path portion.

5. The gas meter according to any one of claims 1 to 3, an inner wall surface of the buffer chamber, when the buffer chamber is viewed in the central axis direction, extends from an inlet of the buffer chamber to which the upstream flow path section is connected, in a direction along a connection direction in which the upstream flow path section is connected to the buffer chamber, and includes a side wall surface located on a side of the inlet of the measurement flow path section, The gas meter, wherein the guide wall portion includes a side guide wall portion that protrudes from the side wall surface toward the inlet of the measurement flow path portion.

6. The gas meter according to any one of claims 1 to 3, an inner wall surface of the buffer chamber includes a back wall surface located opposite an inlet of the buffer chamber to which the upstream flow path section is connected, across an inlet of the measurement flow path section, when the buffer chamber is viewed in the central axis direction; The gas meter, wherein the guide wall portion includes a rear guide wall portion that protrudes from the rear wall surface toward the inlet of the measurement flow path portion.

7. The gas meter according to any one of claims 1 to 3, an inner wall surface of the buffer chamber, when the buffer chamber is viewed in the central axis direction, extends from an inlet of the buffer chamber to which the upstream flow path section is connected in a direction along a connection direction in which the upstream flow path section is connected to the buffer chamber, and includes a side wall surface located on either side of the inlet of the measurement flow path section, and an opposite side wall surface facing the side wall surface across the inlet of the measurement flow path section, The gas meter, wherein the guide wall portion includes an opposite side guide wall portion that protrudes from the opposite side wall surface toward the inlet of the measurement flow path portion.

8. 4. The gas meter according to claim 2 or 3, an inner wall surface of the buffer chamber, when the buffer chamber is viewed in the central axis direction, extends from an inlet of the buffer chamber in a direction along a connecting direction in which the upstream flow path section is connected to the buffer chamber, and includes a side wall surface located on either side of the inlet of the measurement flow path section, and a rear wall surface located opposite the inlet of the buffer chamber across the inlet of the measurement flow path section, The guide wall portion is an inlet guide wall portion that protrudes at an inlet of the buffer chamber connected to the upstream flow path portion so as to face an outlet of the upstream flow path portion; a side guide wall portion protruding from the side wall surface toward the inlet of the measurement flow path portion; a rear guide wall portion protruding from the rear wall surface toward an inlet of the measurement flow path portion; A gas meter comprising:

9. 9. The gas meter according to claim 8, the inner wall surface of the buffer chamber further includes an opposite side wall surface that faces the side wall surface across the inlet of the measurement flow path section when the buffer chamber is viewed in the central axis direction, The gas meter, wherein the guide flow path further includes an opposite side guide wall portion protruding from the opposite side wall surface toward the inlet of the measurement flow path portion.

Images