JP2015145827A - Measurement flow passage unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement flow passage unit capable of suppressing reduction in detection accuracy.SOLUTION: A measurement flow passage unit 2, constituted of a cylindrical body forming a measurement flow passage in which a gas flow velocity is measured by an ultrasonic flow velocity sensor 22, comprises: a multilayer unit 20 having a unit opening 20b passing through the inside and the outside of the cylindrical body; and a mesh plate 21 that is attached to the multilayer unit 20 so as to cover the unit opening 20b. The mesh plate 21 comprises: a plate body 21a having a plate opening 21a1; a mesh that is attached to the plate body 21a so as to cover the plate opening 21a1; and a sensor attaching part 21b which is integrated with the plate body 21a and to which the ultrasonic flow velocity sensor 22 is attached so as to face the plate opening 21a1.

Description

  The present invention relates to a measurement channel unit housed in a gas channel formed inside a gas meter.

  2. Description of the Related Art Conventionally, a gas meter that uses an ultrasonic flow rate sensor to measure the flow rate of gas with ultrasonic waves is known. This gas meter has a main body unit having a predetermined shape which is a metal housing, and the main body unit is provided with a gas inlet connected to a gas supply source and a gas outlet connected to a combustor or the like. In the interior, a series of gas flow paths from the gas inlet to the gas outlet are formed. In this series of gas flow paths, a cylindrical flow path forming portion that forms a measurement flow path for measuring a gas flow rate by an ultrasonic flow rate sensor is disposed. Then, by arranging an ultrasonic flow rate sensor on the side surface of the flow path forming part, the flow rate of the gas flowing in the flow path forming part is measured through the ultrasonic flow rate sensor.

  For example, Patent Document 1 discloses a gas meter using an ultrasonic flow rate sensor. This gas meter has a structure in which an ultrasonic flow velocity sensor is attached to the wall surface of the flow path forming portion.

  Further, for example, Patent Literature 2 discloses a measurement flow path unit that is accommodated in a gas flow path formed inside a gas meter. The measurement channel unit is housed in a gas channel and has a square cylindrical channel forming part that forms a measurement channel for an ultrasonic flow rate sensor. An opening communicating with the measurement channel is formed, and a mesh holder is disposed so as to close the entire opening. The mesh holder has a mesh fixed to a holder opening formed in a part of the mesh holder, and the two ultrasonic flow rate sensors transmit and receive ultrasonic waves through the holder openings of the two mesh holders. The mesh is provided in order to prevent vortices generated in a space formed between the ultrasonic flow rate sensor and the holder opening.

JP 2013-186032 A JP 2005-283565 A

  By the way, according to the method disclosed in Patent Document 1, vortex may be generated in a space formed between the ultrasonic flow rate sensor and the flow path forming unit, and the accuracy of flow rate measurement may be reduced.

  Further, according to the technique disclosed in Patent Document 2, since the ultrasonic flow rate sensor is disposed outside the mesh holder, there is a positional deviation between the flow path forming unit and the ultrasonic flow rate sensor. If it occurs, there is a problem that the measurement accuracy is lowered due to an assembly error.

  This invention is made | formed in view of this situation, The objective is to provide the measurement flow path unit which can suppress the fall of detection accuracy.

  In order to solve this problem, the present invention provides a measurement channel unit accommodated in a gas channel formed inside a gas meter. This measurement flow path unit is formed of a cylindrical body that forms a measurement flow path for measuring a gas flow rate by an ultrasonic flow rate sensor, and has a first opening that penetrates the inside and outside of the cylindrical body. And a mesh plate attached to the flow path forming portion so as to cover the first opening. In this case, the mesh plate is integrated with the plate main body having the second opening, the mesh attached to the plate main body so as to cover the second opening, and the ultrasonic wave so as to face the second opening. A sensor mounting portion for mounting the flow velocity sensor.

  Here, in the present invention, the measurement flow path unit may further include a measurement substrate on which measurement means for measuring the gas flow rate based on the sensor signal from the ultrasonic flow rate sensor is mounted. In this case, it is preferable that the measurement substrate is attached to a substrate attachment part provided in the flow path forming part and integrated with the flow path forming part.

  Further, in the present invention, the substrate attachment portion is composed of a plurality of boss portions erected on the flow path forming portion, and each boss portion is desirably inserted through a hole formed in the measurement substrate.

  Furthermore, in the present invention, it is preferable that the measurement flow path unit further includes a resin cover attached to the flow path forming portion so as to cover the measurement substrate and the sensor attachment portion.

  According to the present invention, the sensor mounting portion is integrally formed on the mesh plate assembled to the flow path forming portion. Therefore, since the ultrasonic flow rate sensor is integrated with the flow path forming portion and is attached to the sensor mounting portion, the ultrasonic flow velocity sensor can be assembled with high accuracy. Moreover, the vortex which arises in the space between an ultrasonic flow rate sensor and 2nd opening can be suppressed by providing a mesh plate in a flow-path formation part. Thereby, the fall of the measurement accuracy of an ultrasonic type flow velocity sensor can be controlled.

Exploded perspective view showing configuration of ultrasonic gas meter Sectional view schematically showing the internal structure of the main unit Perspective view schematically showing the measurement channel unit Exploded perspective view showing the measurement channel unit

  FIG. 1 is an exploded perspective view showing a configuration of an ultrasonic gas meter according to the present embodiment. FIG. 2 is a cross-sectional view schematically showing the internal structure of the main unit 1. The ultrasonic gas meter according to the present embodiment is a gas meter that measures a gas flow rate with an ultrasonic flow rate sensor. The ultrasonic gas meter is mainly composed of a main unit 1, a measurement channel unit 2, a front cover 5, and a control board 6.

  The main unit 1 includes a meter body 10 and an under cover (flow path cover) 15.

  The meter body 10 is a casing in which a series of gas flow paths from the gas inlet 11a to the gas outlet 12a are formed inside the meter body 10. The meter body 10 is made of a metal material such as aluminum or an aluminum alloy. The meter body 10 includes an inlet channel portion 11, an outlet channel portion 12, and an intermediate channel portion 13, and a series of these channel portions 11, 12, 13 bent into a substantially U shape. Gas flow paths are formed.

  The inlet channel portion 11 forms a gas channel extending in the vertical direction, and communicates with a gas inlet 11a through which a gas supply source pipe communicates. The inlet flow passage portion 11 is formed with a cylindrical columnar portion 11b formed so as to extend in the front-rear direction of the drawing, and a shut-off valve 8 described later is provided in the columnar portion 11b.

  The outlet flow channel portion 12 forms a gas flow channel extending in the vertical direction like the inlet flow channel portion 11, and communicates with a gas outlet 12a to which a combustor or the like is connected.

  The intermediate flow path portion 13 forms a gas flow path extending in the left-right direction and communicates with the inlet flow path section 11 and the outlet flow path section 12. The intermediate flow path portion 13 is defined by an under cover 15 described later along with an inverted U-shaped inner wall surface that forms an internal space in the meter body 10.

  An opening 10a is formed on the bottom surface of the meter body 10, and the bottom surface is opened by the opening 10a. The opening portion 10a communicates with the intermediate flow path portion 13, and the internal space of the meter body 10 including the intermediate flow path portion 13 is open to the outside.

  The under cover 15 is a cover member that closes the opening 10 a formed on the bottom surface of the meter body 10. The under cover 15 is formed of a metal material such as aluminum or an aluminum alloy, like the meter body 10.

  The under cover 15 is a plate body having a U-shaped cross section in which a central portion 15a is recessed and formed in a concave shape. The under cover 15 is assembled to the meter body 10 such that a peripheral edge portion 15b positioned around the center portion 15a is abutted against the bottom surface side of the meter body 10. A sealing material 16 (O-ring, gasket, etc.) is interposed between the abutting surfaces of the under cover 15 and the meter body 10, and the meter body 10 and the under cover 15 are mutually connected while keeping the gas passage airtight. It is assembled to.

  A pedestal portion 15 c is formed in the central portion 15 a of the under cover 15. The pedestal portion 15c has a substantially H shape in a top view and is formed to protrude upward. The upper end of the pedestal 15c is positioned inside the meter body 10 corresponding to the intermediate flow path 13, and the measurement flow path unit 2 is placed on the upper end.

  FIG. 3 is a perspective view schematically showing the measurement channel unit 2, and FIG. 4 is an exploded perspective view showing the measurement channel unit 2. The measurement flow path unit 2 includes a multilayer unit 20, two mesh plates 21, two ultrasonic flow rate sensors 22, two sensor fixtures 23, a measurement substrate 24, and a substrate cover 25. Yes. The measurement flow path unit 2 is assembled by integrating various members constituting them, and is placed on the pedestal 15c of the under cover 15 to form a gas flow path (in the meter body 10 ( It is accommodated in the intermediate flow path part 13).

  The multilayer unit 20 is a member that forms a flow path for measuring the flow velocity of the gas flowing through the intermediate flow path portion 13 by the two ultrasonic flow velocity sensors 22, that is, a measurement flow path (flow path forming portion). The multilayer unit 20 is a cylindrical body having a substantially quadrangular cross section that forms a measurement flow path therein, and a plurality of rectifying plates 20a that divide the measurement flow path in the vertical direction are integrated in the cylindrical body. Is formed. The gas flowing through the multilayer unit 20 is rectified by these rectifying plates 20a. The multilayer unit 20 is made of, for example, resin.

  Unit openings (first openings) 20b penetrating the inside and outside of the multilayer unit 20 are formed on two side surfaces of the multilayer unit 20, respectively. The two unit openings 20b are arranged offset in the gas flow direction.

  A mesh plate 21 is disposed in each unit opening 20b. Each mesh plate 21 includes a plate body 21a, a mesh (not shown), and a sensor attachment portion 21b.

  The plate body 21a is a plate having an outer shape corresponding to the unit opening 20b. A plate opening (second opening) 21a1 made of a horizontally long ellipse is formed in the center of the plate body 21a.

  The plate body 21a is attached to the multilayer unit 20 so as to cover the unit opening 20b. Specifically, side wall portions 21a2 connected to the plate main body 21a at a substantially right angle are integrally formed on the pair of long side portions along the gas flow direction in the plate main body 21a. When the plate body 21a is disposed in the unit opening 20b, the upper and lower surfaces of the multilayer unit 20 are sandwiched between the pair of side wall portions 21a2. Here, engagement holes 21a3 are formed in the pair of side wall portions 21a2, and engagement claws 20c are formed on the upper and lower surfaces of the multilayer unit 20 corresponding to the engagement holes 21a3. For this reason, the engagement hole 21a3 and the engagement claw 20c are engaged with each other, the plate body 21a is integrally fixed to the multilayer unit 20, and the unit opening 20b is closed by the plate body 21a in this fixed state.

  The mesh is attached to the plate body 21a so as to cover the plate opening 21a1. The mesh is positioned between the plate body 21 a and the multilayer unit 20. The mesh is provided to prevent vortices generated in the space between the ultrasonic flow rate sensor 22 and the plate opening 21a1. As a method of attaching the mesh, for example, a method of providing a claw on the plate body 21a and fixing it can be considered.

  The sensor attachment portion 21b is a member for attaching the ultrasonic flow rate sensor 22, and is integrally formed outside the plate body 21a. The sensor attachment portion 21b is configured by a cylindrical body having a circular cross section. The sensor attachment portion 21b has one end connected to the plate body 21a so as to communicate with the plate opening 21a1, and a flange portion 21b1 for attaching the ultrasonic flow rate sensor 22 is formed at the other end. Yes. The sensor mounting portion 21b is connected in such a way that its axial direction is connected to the multilayer unit 20 in a predetermined direction, and the ultrasonic flow velocity sensor 22 attached to the sensor mounting portion 21b satisfies the arrangement request. Is set.

  The two ultrasonic flow rate sensors 22 are arranged on the side surfaces of the multilayer unit 20 so as to be separated from each other in the gas flow direction and to form a predetermined angle with the flow direction. Each ultrasonic flow velocity sensor 22 is arranged to face the plate opening 21a1 by being attached to the sensor attachment portion 21b, and transmits and receives ultrasonic waves through the plate opening 21a1.

  The multilayer unit 20 is formed to extend upstream and downstream from the length corresponding to the offset amount of the two ultrasonic flow velocity sensors 22 in the gas flow direction. This is because the purpose is to improve the measurement accuracy of the flow velocity by ensuring a long run-up distance on the upstream side and downstream side of the measurement section by the ultrasonic flow velocity sensor 22.

  The sensor fixture 23 is a member that fixes the ultrasonic flow rate sensor 22 to the sensor mounting portion 21 b, and is positioned outside the ultrasonic flow rate sensor 22. The sensor fixture 23 includes a pair of fixing pieces 23a extending in the direction in which the sensor attachment portion 21b is positioned. An engagement hole 23a1 for engaging with an engagement claw 21b2 formed in the flange portion 21b1 of the sensor mounting portion 21b is formed at the distal end portion of the pair of fixed pieces 23a. When the sensor fixture 23 is attached to the sensor attachment portion 21b through the engagement action between the engagement claw 21b2 and the engagement hole 23a1, the ultrasonic flow rate sensor 22 is sandwiched between the sensor attachment portion 21b. As a result, the ultrasonic flow velocity sensor 22 is fixed and held with respect to the sensor mounting portion 21b.

  The measurement board 24 is attached to a board attachment portion 20 d provided in the multilayer unit 20 and integrated with the multilayer unit 20. In the present embodiment, the board mounting portion 20 d is configured by a plurality of boss portions 20 d 1 erected on the upper surface of the multilayer unit 20. Each boss portion 20d1 is inserted into a through hole 24a formed in the measurement substrate 24 in a position corresponding to the boss portion 20d1, thereby supporting and fixing the measurement substrate 24.

  In the present embodiment, the plurality of boss portions 20d1 are composed of two boss portions 20d1. One boss portion 20d1 is arranged at a substantially central portion on the upper surface of the multilayer unit 20 and the other boss portion 20d1 is arranged on the end portion side of the upper surface of the multilayer unit 20 with reference to the direction perpendicular to the gas flow direction. Yes. Each boss portion 20d1 extends in a direction perpendicular to the gas flow direction and is formed in a rib portion 20d2 having a predetermined height. By this rib portion 20d2, the measurement substrate 24 supported by the boss portion 20d1 is supported in a state separated from the upper surface of the multilayer unit 20 by a certain height.

  The measurement board 24 is equipped with a microcomputer (measuring means) 26 that measures a gas flow rate based on a sensor signal from the ultrasonic flow rate sensor 22, a transmission circuit, a reception circuit, an I / F circuit, and the like (not shown). Yes. The microcomputer 26 is connected to a transmission circuit and a reception circuit, respectively, and the transmission circuit and the reception circuit are connected to the ultrasonic flow rate sensor 22 via an I / F circuit, respectively. For example, the connection between the ultrasonic flow rate sensor 22 and the I / F circuit is performed by a single signal line formed by twisting a plurality of core wires.

  The transmission circuit intermittently transmits a signal for generating an ultrasonic signal under the control of the microcomputer 26 and drives the two ultrasonic flow velocity sensors 22. Therefore, the two ultrasonic flow rate sensors 22 intermittently transmit and receive ultrasonic signals from both the upstream side and the downstream side with respect to the gas flow direction.

  The receiving circuit receives the sensor signal from the other ultrasonic flow velocity sensor 22 that has received the ultrasonic signal that has passed through the measurement flow path. The receiving circuit includes an amplifier that amplifies the sensor signal to a predetermined strength, and the amplification degree of the amplifier can be adjusted by the microcomputer 26. The sensor signal amplified by the amplifier is input to the microcomputer 26.

  When the microcomputer 26 reads the sensor signal at every sampling time, the microcomputer 26 measures the gas flow velocity based on the propagation time of the ultrasonic signals transmitted and received by the two ultrasonic flow velocity sensors 22. The sampling time is, for example, 2 seconds.

  The substrate cover 25 is a resin cover attached to the multilayer unit 20. The board cover 25 accommodates components mounted on the measurement board 24 and signal lines connecting the measurement board 24 and the ultrasonic flow rate sensor 22 inside, and functions to protect them.

  The substrate cover 25 has a plate-like portion 25a corresponding to a shape that covers the measurement substrate 24 and the sensor mounting portion 21b of the mesh plate 21 in a top view, and a peripheral side wall portion that is connected to the entire outer peripheral edge at an angle of substantially right angles. 25b. An engagement hole 25b1 is formed at a predetermined position of the peripheral side wall portion 25b, and an engagement claw 20e is formed on the upper surface of the multilayer unit 20 corresponding to the engagement hole 25b1. The substrate cover 25 is disposed so as to cover the measurement substrate 24 and the sensor mounting portion 21b of the mesh plate 21, and is integrated with the multilayer unit 20 by the engaging action of the engaging hole 25b1 and the engaging claw 20e. The

  Referring to FIG. 1 again, the front cover 5 is a cover that covers the outer surface of the meter body 10. Between the front cover 5 and the outer surface of the meter body 10, a control board 6, a battery 7, a shutoff valve 8, and the like are accommodated. The front cover 5 can be formed of a metal material such as aluminum or an aluminum alloy, like the meter body 10, but can also be formed of a material such as a resin different from the meter body 10.

  A display unit 50 such as an LCD is disposed on the back side of the front cover 5 so as to face the front side from the opening region of the front cover 5, and the display unit 50 is connected to the control board 6. The return button 51 is used to turn on and off a return switch (not shown) by a pressing operation, and outputs a return signal or the like for opening the shutoff valve 8 to the control board 6.

  The control board 6 is attached to the back side of the front cover 5 via a board holding plate 52. The front cover 5 is disposed so as to cover the outer surface of the meter body 10, and the control board 6 is disposed between the outer surface of the meter body 10 and the front cover 5. A battery 7 is attached to the substrate holding plate 52, and electric power necessary for the operation of the gas meter is supplied from the battery 7.

  A microcomputer (control means) 60 for controlling the entire operation of the gas meter is mounted on the control board 6. The microcomputer 60 receives a measurement signal from the measurement substrate 24 (measurement data indicating an instantaneous flow velocity) and a sensor signal from a pressure sensor 61 that detects the pressure in the gas flow path (exit flow path portion 12). . The microcomputer 60 receives measurement data (instantaneous flow velocity data) output from the measurement substrate 24 for each sampling period, and performs arithmetic processing as a gas meter. Specifically, the microcomputer 60 measures the instantaneous flow rate by multiplying the measured gas flow rate by the cross-sectional area of the gas flow path, or calculates an integrated flow rate value that is an integrated value of the measured instantaneous flow rate.

  Connection between the control board 6 and the measurement board 24 is performed via the connector 9. As described above, the measurement substrate 24 is disposed in the flow path in the meter body 10, and the control substrate 6 is disposed on the outer surface side of the meter body 10. The connector 9 is assembled to the meter body 10 so that a part of the connector 9 is exposed in the gas flow path, and is configured to electrically connect the inside and outside of the gas flow path while hermetically sealing the gas flow path. .

  The shut-off valve 8 is a valve for shutting off the gas passage (inlet passage portion 11) and stopping the supply of gas to the combustor or the like connected to the gas meter. The shutoff valve 8 is connected to the control board 6, and the microcomputer 60 controls the shutoff valve 8 based on a signal indicating a gas leak notification from the gas leak alarm or detection of a shutoff event inside the gas meter. To do.

  As described above, the measurement flow path unit 2 of the present embodiment is configured by a cylindrical body that forms a measurement flow path for measuring the gas flow rate by the ultrasonic flow rate sensor 22, and the inside and the outside of the cylindrical body. And the mesh plate 21 attached to the multilayer unit 20 so as to cover the unit opening 20b. Here, the mesh plate 21 is integrated with the plate body 21a including the plate opening 21a1, the mesh attached to the plate body 21a so as to cover the plate opening 21a1, and the plate body 21a so as to face the plate opening 21a1. And a sensor attachment portion 21b for attaching the ultrasonic flow velocity sensor 22 to the sensor.

  In order to accurately measure the flow velocity by the ultrasonic flow velocity sensor 22, the positional accuracy of the ultrasonic flow velocity sensor 22 with respect to the multilayer unit 20 is required. When the ultrasonic flow velocity sensor 22 is attached to the under cover 15, the multilayer unit 20 and the under cover 15 to which the ultrasonic flow velocity sensor 22 is attached are physically separated. Misalignment may occur. For this reason, there is a problem in that a positional deviation also occurs between the multilayer unit 20 and the ultrasonic flow velocity sensor 22 due to an assembly error between them, thereby reducing the measurement accuracy. Further, since the under cover 15 is generally formed of a metal material or the like, high processing accuracy is required to attach the ultrasonic flow rate sensor 22 with high accuracy, and the manufacturing process becomes complicated and costly. There is a problem of increasing.

  However, according to the measurement flow path unit 2 of the present embodiment, the sensor mounting portion 21b is integrally formed on the mesh plate 21 (plate body 21a) assembled to the multilayer unit 20. Therefore, since the ultrasonic flow rate sensor 22 is integrated with the multi-layer unit 20 and the sensor mounting portion 21b, the ultrasonic flow rate sensor 22 can be assembled with high accuracy. Moreover, by providing the mesh plate 21 in the multiphase unit 20, vortices generated in the space between the ultrasonic flow rate sensor 22 and the plate opening 21a1 can be suppressed. Thereby, the fall of the measurement precision of the ultrasonic type flow velocity sensor 22 can be suppressed.

  The measurement channel unit 2 of the present embodiment further includes a measurement board 24 on which a microcomputer 26 that measures a gas flow rate based on a sensor signal from the ultrasonic flow rate sensor 22 is mounted. The multi-layer unit 20 is integrated with the multi-layer unit 20 by being attached to the board mounting portion 20 d provided in the multi-layer unit 20.

  According to this configuration, since the measurement substrate 24 is integrated with the multilayer unit 20, the ultrasonic flow rate sensor 22 and the measurement substrate 24 can be collectively arranged. For this reason, the wiring (signal line) from the ultrasonic flow rate sensor 22 to the measurement substrate 22 can be shortened. Since the sensor signal is a weak analog signal, if the wiring is long, the influence of noise is likely to be included. However, according to the present embodiment, a configuration that is hardly affected by noise can be realized. Thereby, the fall of detection accuracy can be suppressed.

  In the present embodiment, the board mounting portion 20d is composed of a plurality of boss portions 20d1 erected on the multilayer unit 20, and each boss portion 20d1 is inserted through a hole 26a formed in the measurement substrate 26. ing.

  According to this configuration, if the positional relationship between the through hole 24a of the measurement substrate 24 and the boss portion 20d1 does not match, the measurement substrate 24 cannot be inserted through all the boss portions 20d1. For this reason, it is possible to prevent erroneous assembly in which the measurement board 24 to be assembled to the multilayer unit 20 in a predetermined direction is assembled in an incorrect direction.

  In the present embodiment, the measurement channel unit 2 further includes a resin substrate cover 52 attached to the multilayer unit 20 so as to cover the measurement substrate 24 and the sensor attachment portion 21b.

  According to this configuration, the wiring from the ultrasonic flow rate sensor 22 to the measurement substrate 24 is covered with the resin substrate cover 52. When the wiring touches the meter body 10 which is a metal casing, this causes noise. However, according to the present embodiment, contact between the wiring and the meter body 10 and other metal parts is suppressed by the substrate cover 52, so that noise is suppressed. Thereby, the fall of measurement accuracy can be controlled.

  Although the gas meter according to the present embodiment has been described above, the present invention is not limited to this embodiment, and various modifications can be made within the scope of the present invention. Further, not only the measurement channel unit but also a gas meter that accommodates it in the gas channel functions as part of the present invention.

DESCRIPTION OF SYMBOLS 1 Main body unit 10 Meter body 10a Opening part 11 Inlet flow path part 11a Gas inflow port 12 Outlet flow path part 12a Gas outflow part 13 Intermediate flow path part 15 Undercover 15c Base part 2 Measurement flow path unit 20 Multilayer unit 20b Unit opening 20d Board mounting part 20d1 Boss part 20d2 Rib part 20e Engaging claw 21 Mesh plate 21a Plate body 21a1 Plate opening 21a2 Side wall part 21b Sensor mounting part 21b1 Flange part 22 Ultrasonic flow rate sensor 23 Sensor fixture 24 Measurement board 24a Hole 25 Board cover 26 Microcomputer 5 Front cover 6 Control board 60 Microcomputer 9 Connector

Claims (4)

In the measurement flow path unit accommodated in the gas flow path formed inside the gas meter,
A flow path forming section comprising a cylindrical body forming a measurement flow path for measuring a gas flow rate by an ultrasonic flow rate sensor, and having a first opening penetrating the inside and outside of the cylindrical body;
A mesh plate attached to the flow path forming portion so as to cover the first opening,
The mesh plate is
A plate body with a second opening;
A mesh attached to the plate body so as to cover the second opening;
A sensor mounting portion that is integrated with the plate body and attaches the ultrasonic flow velocity sensor so as to face the second opening;
A measurement flow path unit comprising: Further comprising a measurement board equipped with measurement means for measuring a gas flow rate based on a sensor signal from the ultrasonic flow rate sensor;
The measurement channel unit according to claim 1, wherein the measurement substrate is attached to a substrate attachment part provided in the channel formation part and integrated with the channel formation part.   The substrate mounting portion is composed of a plurality of boss portions standing on the flow path forming portion, and each boss portion is inserted through a hole formed in the measurement substrate. 2. The measurement channel unit described in 2.   The measurement flow path unit according to claim 2 or 3, further comprising a resin cover attached to the flow path forming portion so as to cover the measurement substrate and the sensor attachment portion.