Ultrasonic measurement unit

Abstract

To provide an ultrasonic measurement unit capable of improving measurement accuracy.SOLUTION: An ultrasonic measurement unit 14 includes: a flow path section 41 which has a measurement flow path 54; a plurality of partition plates 47 which each extend in a flow direction; a pair of ultrasonic transmitter / receiver fixing sections 43; a pair of transmission sections 42 which each include an opening formed in a wall section 55 connecting an ultrasonic propagation section 61 of the ultrasonic transmitter / receiver fixing section 43 to the measurement flow path 54 and through which ultrasonic waves transmitted to and received from an ultrasonic transmitter / receiver 32 propagate; a circuit board 33; and a circuit board fixing section 34 which holds the circuit board 33. The flow path section 41, the plurality of partition plates 47, the pair of ultrasonic transmitter / receiver fixing sections 43, and the pair of transmission sections 42 are integrally formed as a main body block 31.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic measurement unit. [Background technology]

[0002] BACKGROUND ART Conventionally, flow rate measurement units for measuring the flow rate of fluids such as gases used in gas meters have been known (see, for example, Patent Document 1).

[0003] This flow rate measurement unit includes a flow path block and a measurement block that holds a pair of ultrasonic transmitters and receivers. The flow path block has a flow path for a fluid, a permeable membrane with two permeable openings, and a sensor base that is an adapter for attaching the measurement block to the flow path block. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-159627 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the flow rate measurement unit described in Patent Document 1 sometimes suffers from leakage of the fluid to be measured from the gap between the flow path block and the sensor base. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, an ultrasonic measurement unit according to an aspect of the present invention includes a flow path section through which a fluid to be measured flows, the flow path section including a wall section including a first longitudinal wall section and a second longitudinal wall section extending in a longitudinal direction as viewed from a flow direction in which the fluid to be measured flows and a pair of side wall sections extending in a lateral direction intersecting the longitudinal direction as viewed from the flow direction, and a measurement flow path defined by the wall sections; a pair of ultrasonic transmitter / receivers each having a plurality of partition plates disposed between the pair of side wall sections and each extending in the flow direction; and a pair of ultrasonic transmitter / receivers each having a holding section disposed on the first longitudinal wall section for holding an ultrasonic transmitter / receiver and an ultrasonic propagation section including an internal space of the holding section. a circuit board having a transducer fixing portion, a pair of transmission portions each including an opening formed in the wall portion through which ultrasonic waves transmitted and received from the ultrasonic transmitter / receiver propagate, communicating between the ultrasonic propagation portion of the ultrasonic transmitter / receiver fixing portion and the measurement flow path, a measurement portion that measures the propagation time of ultrasonic waves from one ultrasonic transmitter / receiver to the other ultrasonic transmitter / receiver, and a calculation portion that calculates the flow rate of the fluid to be measured based on the propagation time measured by the measurement portion; and a circuit board fixing portion that holds the circuit board, wherein the flow path portion, the multiple partition plates, the pair of ultrasonic transmitter / receiver fixing portions, and the pair of transmission portions are integrally formed as a main body block.

[0007] According to this configuration, it is possible to suppress the occurrence of leakage of the fluid to be measured, and to improve the measurement accuracy. [Effects of the Invention]

[0008] The present invention has an effect of improving measurement accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of a gas meter according to a first embodiment. [Figure 2] 2 is an exploded perspective view showing an example of the configuration of a measurement unit, a connection joint, and a seal member of the gas meter of FIG. 1. FIG. [Figure 3] FIG. 2 is a cross-sectional view showing an example of the configuration of a measurement unit of the gas meter of FIG. [Figure 4] FIG. 2 is a perspective view showing an example of the configuration of a main body block of the gas meter of FIG. [Figure 5] 10A to 10C are diagrams showing an example of the configuration of a measurement unit of a gas meter according to a second embodiment, and are, from top to bottom, a front view, a rear view, a plan view, and a bottom view. [Figure 6] 6A and 6B are diagrams showing an example of the configuration of the measurement unit of FIG. 5, and are, from top to bottom, a left side view, a right side view, and a perspective view 1. FIG. [Figure 7] 6 is a diagram showing an example of the configuration of the measurement unit of FIG. 5, and is, from above, a perspective view 2 and a reference perspective view showing a state of use. [Figure 8] 10A to 10C are diagrams showing an example of the configuration of a measurement unit of a gas meter according to a third embodiment, and are, from top to bottom, a front view, a rear view, a plan view, and a bottom view. [Figure 9] 9A and 9B are diagrams showing an example of the configuration of the measurement unit of FIG. 8, and are, from top to bottom, a left side view, a right side view, and a perspective view 1. FIG. [Figure 10] 9 is a diagram showing an example of the configuration of the measurement unit of FIG. 8, and is, from the top, a perspective view 2 and a reference perspective view 1 showing the state of use. [Figure 11] 9 is a diagram showing a configuration example of the measurement unit of FIG. 8, and is a reference perspective view 2 showing a state of use. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments. In addition, the same or corresponding elements will be denoted by the same reference numerals throughout the drawings, and redundant description will be omitted.

[0011] (Embodiment 1) FIG. 1 is a cross-sectional view showing an example of the configuration of a gas meter 100 according to the first embodiment.

[0012] As shown in Fig. 1, the gas meter 100 is a flow measurement device that can measure the flow rate of a fluid to be measured, such as city gas or liquefied petroleum gas. The measured flow rate of the fluid to be measured can be used as the basis for calculating fees. In this embodiment, the gas meter 100 is suitable for industrial use (business use) and is compatible with higher flow rates than those for residential use.

[0013] The gas meter 100 includes a meter box 11, a meter inlet 12, a meter outlet 13, an ultrasonic measurement unit 14, a pipe 15, a seal member 16, two fixed shafts 17, and a shutoff valve 19.

[0014] The metering box 11 is a container that forms the outer shell of the gas meter 100. The metering box 11 has an internal space 24 that is filled with gas.

[0015] Meter inlet portion 12 is a mouthpiece connected to a gas supply pipe, and is the portion through which the fluid to be measured is introduced into internal space 24 of metering box 11. Meter inlet portion 12 has inlet 26. Inlet 26 is an opening through which the fluid to be measured flows into metering box 11.

[0016] Meter outlet 13 is a nozzle that is connected to the building's piping, and is the part that discharges the fluid to be measured that has been measured by ultrasonic measurement unit 14 to the outside. Meter outlet 13 has outlet 27. Outlet 27 is an opening through which the fluid to be measured that has flowed into meter inlet 12 flows out of measurement box 11.

[0017] 2 is an exploded perspective view showing an example of the configuration of the ultrasonic measurement unit 14, the pipe 15, and the seal member 16. The ultrasonic measurement unit 14 is an ultrasonic measurement unit that measures the flow rate of the fluid to be measured. The ultrasonic measurement unit 14 is housed in the measurement box 11. In this embodiment, the ultrasonic measurement unit 14 is an ultrasonic measurement unit, and as shown in FIG. 2, is a device that transmits and receives ultrasonic waves between two ultrasonic transmitter / receivers 32 to measure the propagation time of the ultrasonic waves, calculates the flow rate of the fluid to be measured based on the measured propagation time, and outputs the calculated flow rate.

[0018] The piping 15 connects the ultrasonic measurement unit 14 and the meter outlet 13. The piping 15 is a tubular body that defines a flow path through which the fluid to be measured flows. The piping 15 includes two pairs of piping-side through holes 89. The pair of piping-side through holes 89 are arranged coaxially with each other.

[0019] The sealing member 16 is a member that is sandwiched between the ultrasonic measuring unit 14 and the piping 15 so as to fill the gap between the ultrasonic measuring unit 14 and the piping 15. The material of the sealing member 16 is an elastic body such as rubber.

[0020] The fixed shaft 17 is a member that is inserted into the pipe-side through-hole 89 and the measurement unit-side through-hole 62 (described later) to connect the ultrasonic measurement unit 14 and the pipe 15 and fix the ultrasonic measurement unit 14 to the pipe 15. The fixed shaft 17 has two pin insertion holes 93 at both ends to which pins 94, which are snap pins, are attached.

[0021] As shown in FIG. 1, the shutoff valve 19 is attached to the meter inlet portion 12, and shuts off the flow of the fluid to be measured into the measurement box 11 when the control portion of the gas meter 100 determines that there is an abnormality such as a gas leak.

[0022] Next, the ultrasonic measurement unit 14 will be described in detail. Fig. 3 is a cross-sectional view showing an example configuration of the ultrasonic measurement unit 14. As shown in Figs. 2 and 3, the ultrasonic measurement unit 14 includes a main body block 31, a circuit board fixing portion 34, a pin 70 for attaching the circuit board fixing portion 34 to the main body block 31, two ultrasonic transmitter / receivers 32, a circuit board 33, two ultrasonic transmitter / receiver fixing devices 35, and a cover 74.

[0023] Fig. 4 is a perspective view showing an example of the configuration of the main body block 31. The main body block 31 is a member integrally formed from a resin material. As shown in Figs. 3 and 4, the main body block 31 includes a flow path section 41, a plurality of partition plates 47, two ultrasonic transmitter / receiver fixing sections 43, two transmission sections 42, and an attachment section 44.

[0024] The flow path section 41 surrounds a measurement flow path 54 through which the fluid to be measured flows, and defines the measurement flow path 54. The flow path section 41 includes a wall section 55 which is a cylindrical body extending in the flow direction DF of the fluid to be measured, a funnel section 45, and a measurement unit side connection section 46. The wall section 55 has a substantially rectangular cross section with respect to the flow direction DF, and has a longitudinal direction DL and a lateral direction DS. The longitudinal direction DL is a direction intersecting or perpendicular to the flow direction DF. The lateral direction DS is a direction intersecting or perpendicular to the flow direction DF and the longitudinal direction DL. The wall section 55 includes a first longitudinal wall section 51, a second longitudinal wall section 52, and two side wall sections 53. The cross-sectional area of ​​the measurement flow path 54 is, for example, 400 mm 2 As a result, the cross-sectional area is larger than that of a gas meter for home use.

[0025] The first longitudinal wall 51 is a wall extending in the longitudinal direction DL when viewed from the flow direction DF. In this embodiment, the first longitudinal wall 51 is located on a plane extending in the longitudinal direction DL and the flow direction DF. The second longitudinal wall 52 is a wall extending parallel to the first longitudinal wall 51 and facing the first longitudinal wall 51. The two side wall 53 are walls extending in the lateral direction DS when viewed from the flow direction DF. In this embodiment, the two side wall 53 are located on a plane extending in the lateral direction DS and the flow direction DF. One side wall 53 connects one side edge of the two first longitudinal wall 51. The other side wall 53 connects the other side edge of the two first longitudinal wall 51.

[0026] The funnel portion 45 is located at the upstream end of the flow path portion 41 in the flow direction DF. The measurement flow path 54 has a shape in which the cross-sectional area decreases from the upstream side to the downstream side in the flow direction DF of the measurement flow path 54, causing the measurement target fluid to contract from the upstream side to the downstream side in the flow direction DF. The funnel portion 45 has the effect of suppressing turbulence in the measurement target fluid and making the flow velocity distribution uniform. As a result, the funnel portion 45 contributes to improving measurement accuracy.

[0027] The measurement unit side connection part 46 is a part that is connected to the piping 15. The measurement unit side connection part 46 is located at the downstream end of the main body block 31 in the flow direction DF. The measurement unit side connection part 46 is a frame-shaped part that protrudes outward from the outer peripheral surface of the downstream end of the main body block 31 in the flow direction DF, and is located so as to surround the outlet of the measurement flow path 54. The measurement unit side connection part 46 includes a recess 63 and two measurement unit side through holes 62.

[0028] The recess 63 is a portion recessed toward the upstream side from the surface facing the downstream side of the flow direction DF of the measurement unit side connection portion 46, and is an annular groove surrounding the outlet of the measurement flow path 54. The recess 63 is a portion into which the seal member 16 is fitted.

[0029] The two measurement unit side through holes 62 are through holes through which the fixed shafts 17 are inserted. The measurement unit side through holes 62 are located on the upstream side of the recess 63 in the flow direction DF. The measurement unit side through holes 62 extend, for example, in a direction perpendicular to the flow direction DF. More specifically, the measurement unit side through holes 62 extend in the short direction DS.

[0030] The partition plates 47 are disposed between the two side wall portions 53 and are each a plate-like body extending in the flow direction DF. The partition plates 47 are arranged in the longitudinal direction DL. By dividing the internal space in the measurement flow path 54, the partition plates 47 have the effect of suppressing turbulence in the fluid to be measured and making the flow velocity distribution uniform. As a result, the partition plates 47 contribute to improving measurement accuracy.

[0031] The two ultrasonic transmitter / receiver fixing portions 43 are arranged on the first longitudinal wall portion 51. The ultrasonic transmitter / receiver fixing portion 43 is formed in a short cylindrical shape protruding from the first longitudinal wall portion 51, with its base end connected to the first longitudinal wall portion 51 and its tip portion forming a holding portion 59 that holds the ultrasonic transmitter / receiver 32. The two ultrasonic transmitter / receiver fixing portions 43 are aligned in the flow direction DF. One of the two ultrasonic transmitter / receiver fixing portions 43 holds the ultrasonic transmitter / receiver 32 so that the wave transmission direction of the ultrasonic transmitter / receiver 32 faces toward the second longitudinal wall portion 52 and downstream. The other of the two ultrasonic transmitter / receiver fixing portions 43 holds the ultrasonic transmitter / receiver 32 so that the wave transmission direction of the ultrasonic transmitter / receiver 32 faces toward the second longitudinal wall portion 52 and upstream. The internal space of the ultrasonic transmitter / receiver fixing portion 43 forms an ultrasonic wave propagation portion 61, which is a space through which the ultrasonic waves transmitted from the ultrasonic transmitter / receiver 32 propagate.

[0032] The two transmission sections 42 are openings formed in the first longitudinal wall section 51. The two transmission sections 42 are positioned side by side in the flow direction DF of the fluid to be measured. The two transmission sections 42 are positioned between the ultrasonic propagation section 61 and the measurement flow path 54, and communicate with the ultrasonic propagation section 61 and the measurement flow path 54. The two transmission sections 42 each form a space through which ultrasonic waves transmitted and received from the ultrasonic transmitter / receiver 32 propagate.

[0033] The ultrasonic waves transmitted by the upstream ultrasonic transmitter / receiver 32 pass through the upstream ultrasonic propagation portion 61 and the transmission portion 42, enter the measurement flow path 54, and are reflected at least once by the inner surface of the second longitudinal wall portion 52. The ultrasonic waves reflected by the second longitudinal wall portion 52 then pass through the downstream transmission portion 42 from the measurement flow path 54, enter the downstream ultrasonic propagation portion 61, and are detected by the downstream ultrasonic transmitter / receiver 32. The ultrasonic waves transmitted by the downstream ultrasonic transmitter / receiver 32 also pass through the downstream ultrasonic propagation portion 61 and the transmission portion 42, enter the measurement flow path 54, and are reflected at least once by the second longitudinal wall portion 52. The ultrasonic waves reflected by the second longitudinal wall portion 52 then pass through the upstream transmission portion 42 from the measurement flow path 54, enter the upstream ultrasonic propagation portion 61, and are detected by the upstream ultrasonic transmitter / receiver 32.

[0034] The mounting portion 44 is a portion to which the circuit board fixing portion 34 is attached and which holds the circuit board fixing portion 34. The mounting portion 44 is located between the two ultrasonic transmitter / receiver fixing portions 43. The mounting portion 44 has an engagement shaft 67 that protrudes outward from the outer surface of the first longitudinal wall portion 51. The engagement shaft 67 has a pin insertion hole 68 formed at its tip. The pin insertion hole 68 is a through hole that extends in a direction that intersects or is perpendicular to the engagement shaft 67.

[0035] The circuit board fixing portion 34 is a member that holds the circuit board 33. The circuit board fixing portion 34 is a member that is independent from the main body block 31. The circuit board fixing portion 34 has an engagement hole 69 through which an engagement shaft 67 is inserted. When the circuit board fixing portion 34 is attached to the attachment portion 44, the tip of the engagement shaft 67 of the attachment portion 44 and the pin insertion hole 68 protrude outward from the engagement hole 69 of the circuit board fixing portion 34. A pin 70, which is a snap pin, is removably attached to the pin insertion hole 68. This restricts movement of the circuit board fixing portion 34 and fixes it to the main body block 31.

[0036] The ultrasonic transmitter / receiver 32 includes an ultrasonic transmitting element. When a drive signal is input to the ultrasonic transmitting element, the element transmits ultrasonic waves in a predetermined transmitting direction in response to the drive signal to the outside. When an ultrasonic wave is received from the outside, the ultrasonic oscillation element outputs a detection voltage in response to the received ultrasonic waves. As such an ultrasonic oscillation element, a known ultrasonic oscillation element can be used, such as a known piezoelectric ceramic vibrator.

[0037] The circuit board 33 is connected to the two ultrasonic transmitter / receivers 32 via lead wires. The circuit board 33 drives the two ultrasonic transmitter / receivers 32. The circuit board 33 includes a measurement unit and a calculation unit. The measurement unit measures the propagation time of ultrasonic waves from one ultrasonic transmitter / receiver 32 to the other ultrasonic transmitter / receiver 32. More specifically, the measurement unit measures a first propagation time of ultrasonic waves traveling from the upstream ultrasonic transmitter / receiver 32 to the downstream ultrasonic transmitter / receiver 32, and a second propagation time of ultrasonic waves traveling from the downstream ultrasonic transmitter / receiver 32 to the upstream ultrasonic transmitter / receiver 32. The calculation unit calculates the flow rate of the fluid to be measured flowing through the measurement flow path 54 based on the propagation times measured by the measurement unit. More specifically, the difference between the first propagation time and the second propagation time is proportional to the flow velocity of the fluid to be measured. Therefore, the calculation unit calculates the flow velocity based on the difference between the first propagation time and the second propagation time, and calculates the flow rate by multiplying the calculated flow velocity by the known cross-sectional area of ​​the measurement flow path 54. The circuit board 33 is disposed parallel to the flow direction DF and is positioned so as to straddle the two ultrasonic transmitter / receivers 32. The circuit board 33 is provided with a connector for outputting measurement information to the outside. The connector is a member for electrically connecting the circuit board 33 to an external device of the gas meter 100, and has the function of stably transmitting measurement information signals via multiple contact points. A communication cable extending outside the gas meter 100 is connected to the connector. As a result, the measurement information generated by the circuit board 33 is transmitted to the communication cable via the connector and sent to the external device.

[0038] The two ultrasonic transmitter / receiver fixing devices 35 are members that fix the ultrasonic transmitter / receiver 32 held by the holding parts 59 of the ultrasonic transmitter / receiver fixing part 43, and have the function of restricting movement of the ultrasonic transmitter / receiver 32 relative to the ultrasonic transmitter / receiver fixing part 43. The ultrasonic transmitter / receiver fixing devices 35 sandwich the ultrasonic transmitter / receiver 32 between themselves and the holding parts 59. This allows the ultrasonic transmitter / receiver 32 to be stably fixed against vibrations and external forces. The ultrasonic transmitter / receiver fixing devices 35 are detachably attached to the ultrasonic transmitter / receiver fixing part 43.

[0039] The cover 74 covers the circuit board 33 and the two ultrasonic transmitter / receivers 32, and protects the circuit board 33 and the two ultrasonic transmitter / receivers 32 from moisture, etc. The cover 74 is detachably attached to the main body block 31 or the circuit board fixing portion 34.

[0040] 4, the maximum dimension ML1 in the longitudinal direction DL of the end portion on the outlet side of the measurement flow path 54 of the flow path portion 41, i.e., the measurement unit side connection portion 46, is the same as the maximum dimension ML2 in the longitudinal direction DL of the end portion on the inlet side of the measurement flow path 54 of the ultrasonic measurement unit 14, i.e., the funnel portion 45. Furthermore, the maximum dimension MS1 ​​in the lateral direction DS of the measurement unit side connection portion 46 is the same as the maximum dimension MS2 in the lateral direction DS of the funnel portion 45. This makes it possible to prevent the funnel portion 45 and the measurement unit side connection portion 46, which extend outward beyond the wall portion 55 when viewed from the flow direction DF, from interfering with the surrounding environment.

[0041] When connecting the ultrasonic measurement unit 14 to the piping 15, the seal member 16 is fitted into the recess 63 of the ultrasonic measurement unit 14. Then, the measurement unit side connection part 46 is pressed against the ultrasonic measurement unit 14, and the two fixed shafts 17 are inserted into the two pairs of piping side through-holes 89 and the two measurement unit side through-holes 62. This allows the fixed shafts 17 to be stably positioned.

[0042] As described above, the main body block 31 of the ultrasonic measurement unit 14 of this embodiment is integrally formed with the flow path section 41, the partition plate 47, the pair of ultrasonic transmitter / receiver fixing sections 43, and the transmission section 42. This makes it possible to suppress leakage of the fluid to be measured and improve measurement accuracy.

[0043] Furthermore, the ultrasonic transmitter / receiver fixture 35 is a member independent of the main body block 31, and is attached to the attachment portion 44 of the main body block 31. This simplifies the configuration of the main body block 31 for the portion related to the attachment structure of the circuit board 33, which does not affect leakage of the fluid to be measured. This is also advantageous for manufacturing, and reduces manufacturing costs.

[0044] (Embodiment 2) A measurement unit according to the second embodiment is shown in Figs. 5 to 7. Fig. 5 is a diagram showing an example of the configuration of a measurement unit of a gas meter according to the second embodiment, and is, from top to bottom, a front view, a rear view, a plan view, and a bottom view. Fig. 6 is, from top to bottom, a left side view, a right side view, and a perspective view 1. Fig. 7 is, from top to bottom, a perspective view 2 and a reference perspective view showing the state of use.

[0045] (Embodiment 3) A measurement unit according to the third embodiment is shown in Figs. 8 to 11. Fig. 8 is a diagram showing an example of the configuration of a measurement unit of a gas meter according to the third embodiment, and is, from top to bottom, a front view, a rear view, a plan view, and a bottom view. Fig. 9 is, from top to bottom, a left side view, a right side view, and a perspective view 1. Fig. 10 is, from top to bottom, a perspective view 2 and a reference perspective view 1 showing the state of use. Fig. 11 is a reference perspective view 2 showing the state of use.

[0046] From the above description, many modifications and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present invention.

[0047] (Other embodiments) (Technology 1) The ultrasonic measurement unit of Technology 1 includes a flow path section through which a fluid to be measured flows, the flow path section having a wall section including a first longitudinal wall section and a second longitudinal wall section extending in a longitudinal direction as viewed from a flow direction in which the fluid to be measured flows and a pair of side wall sections extending in a lateral direction intersecting the longitudinal direction as viewed from the flow direction, and a measurement flow path defined by the wall sections; a pair of ultrasonic transmitter / receiver fixing sections each having a plurality of partition plates disposed between the pair of side wall sections and each extending in the flow direction; and a pair of ultrasonic transmitter / receiver fixing sections each disposed on the first longitudinal wall section and each having an ultrasonic propagation section including a holding section for holding an ultrasonic transmitter / receiver and an internal space of the holding section; The fluid path section, the plurality of partition plates, the pair of ultrasonic transmitter / receiver fixing parts, and the pair of transmitting parts are integrally formed into a main body block. The main body block comprises a circuit board having a pair of transmitting parts, each of which includes an opening formed in the wall part through which ultrasonic waves transmitted and received from the ultrasonic transmitter / receiver are propagated, communicating between the ultrasonic propagation part of the ultrasonic transmitter / receiver fixing part and the measurement flow path, a measuring part that measures the propagation time of the ultrasonic waves from one ultrasonic transmitter / receiver to the other ultrasonic transmitter / receiver, and a calculating part that calculates the flow rate of the fluid to be measured based on the propagation time measured by the measuring part, and a circuit board fixing part that holds the circuit board.

[0048] (Technology 2) The ultrasonic measurement unit of Technology 2 is the ultrasonic measurement unit described in Technology 1, in which the circuit board fixing portion is a member independent from the main body block, and the main body block has an attachment portion to which the circuit board fixing portion is attached.

[0049] (Technology 3) The ultrasonic measurement unit of Technology 3 is the ultrasonic measurement unit described in Technology 1 or 2, wherein the flow path portion has a funnel portion located at the upstream end of the measurement flow path in the flow direction and contracting the measured fluid from the upstream side toward the downstream side in the flow direction, and a connection portion located at the downstream end of the measurement flow path in the flow direction and connected to a pipe through which the measured fluid flows, wherein the maximum longitudinal dimensions of the funnel portion and the connection portion are the same, and the maximum lateral dimensions of the funnel portion and the connection portion are the same. [Explanation of symbols]

[0050] 14 Ultrasonic measurement unit 31 Main body block 32 Ultrasonic Transmitter / Receiver 33 Circuit Board 34 Circuit board fixing part 35 Ultrasonic transducer fixture 41 Flow path section 42 Transparent part 43 Ultrasonic transmitter / receiver fixing part 47 Partition 51 First longitudinal wall 52 Second longitudinal wall 53 Side wall 54 Measurement flow path 55 Wall 59 Holding part 61 Ultrasound propagation section 67 Engagement shaft 100 Gas Meter

Claims

1. a flow path portion through which a fluid to be measured flows, the flow path portion including a wall portion including a first longitudinal wall portion and a second longitudinal wall portion extending in a longitudinal direction as viewed from a flow direction in which the fluid to be measured flows and a pair of side wall portions extending in a lateral direction intersecting the longitudinal direction as viewed from the flow direction, and a measurement flow path defined by the wall portion; a plurality of partition plates disposed between the pair of side wall portions and each extending in the flow direction; a pair of ultrasonic transmitter / receiver fixing portions each disposed on the first longitudinal wall portion and each including a holding portion for holding an ultrasonic transmitter / receiver and an ultrasonic propagation portion including an internal space of the holding portion; a pair of transmission sections each including an opening formed in the wall section through which ultrasonic waves transmitted and received from the ultrasonic transmitter / receiver propagate, the opening communicating between the ultrasonic propagation section of the ultrasonic transmitter / receiver fixing section and the measurement flow path; a circuit board having a measuring unit that measures the propagation time of ultrasonic waves from one of the ultrasonic transmitter-receivers to the other of the ultrasonic transmitter-receivers, and a calculating unit that calculates the flow rate of the fluid to be measured based on the propagation time measured by the measuring unit; a circuit board fixing portion for holding the circuit board, The ultrasonic measuring unit is a main body block in which the flow path portion, the plurality of partition plates, the pair of ultrasonic transmitter / receiver fixing portions, and the pair of transmission portions are integrally formed.

2. the circuit board fixing portion is a member independent of the main body block, 2. The ultrasonic measurement unit according to claim 1, wherein the main body block has a mounting portion to which the circuit board fixing portion is attached.

3. The flow path portion is a funnel portion located at an upstream end of the measurement flow path in the flow direction and causing the measurement target fluid to contract from the upstream side toward the downstream side in the flow direction; and a connection portion located at a downstream end of the measurement flow path in the flow direction and connected to a pipe through which the measurement target fluid flows, 3. The ultrasonic measuring unit according to claim 1, wherein the funnel portion and the connecting portion have the same maximum longitudinal dimension, and the funnel portion and the connecting portion have the same maximum lateral dimension.

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