JP2015129723A - Measurement unit and flow rate measurement apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement unit capable of improving measurement accuracy of a flow rate measurement apparatus.SOLUTION: A measurement unit 35 is a measurement unit used in a flow rate measurement apparatus which measures the flow rate of a fluid flowing through a cylindrical measurement flow path 26. The measurement unit 35 includes: a pair of ultrasonic transmitting-receiving devices 38 that transmit and receive ultrasonic waves with each other; a circuit board 36 which is electrically connected to the ultrasonic transmitting-receiving devices; and a holding member 70 which includes a circuit board holder for holding the circuit board, a sensor holder for holding the pair of ultrasonic transmitting-receiving devices so as to fix the relative position with each other, and engaging part for engaging with the measurement flow path.

Description

  The present invention relates to a measurement unit and a flow rate measurement apparatus including the measurement unit, and in particular, in a cylindrical measurement flow path unit that is housed in a fluid flow path unit and communicates with the fluid flow path unit. The present invention relates to a flow rate measurement device that measures the flow rate of a fluid flowing through the flowmeter, and a measurement unit used therefor.

  As a conventional flow rate measurement device, a flow rate measurement device using a measurement flow path unit housed in a fluid flow path unit is known. For example, in the flow rate measuring device shown in Patent Document 1, a measurement flow path section around which a rubber band is wound is accommodated in a gas flow path section, and two flow velocity sensors are arranged on the side surface of the measurement flow path section. This rubber band closes the gap between the inner surface of the gas flow path section and the outer surface of the measurement flow path section, guides the gas in the gas flow path section to the measurement flow path section, and controls the flow rate of the gas flowing through the measurement flow path section. Measured with a flow rate sensor.

JP 2005-283565 A

  However, in the conventional flow rate measuring device such as Patent Document 1, since the flow rate sensor is arranged away from the electric circuit that measures the flow rate, the length of the lead wire that connects the flow rate sensor and the electric circuit is large. Become. As a result, the possibility of external noise intruding into the lead wire increases, leading to a decrease in measurement accuracy due to the noise.

  In addition, if each of the two ultrasonic transducers is arranged, the measurement accuracy of the flow rate measuring device is lowered due to the error of the relative position.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a measurement unit that improves measurement accuracy and a flow rate measurement apparatus including the measurement unit.

  A measurement unit according to an aspect of the present invention is a measurement unit used in a flow measurement device that measures the flow rate of a fluid flowing through a cylindrical measurement flow path unit, and a pair of ultrasonic transmission / reception waves that transmit and receive ultrasonic waves to and from each other. , A substrate that is electrically connected to the ultrasonic transducer, a substrate holding unit that supports the substrate, and a sensor that supports the pair of ultrasonic transducers so that their relative positions are fixed to each other And a holding member having a holding part and a locking part for locking the measurement flow path part.

  The present invention has an effect that it is possible to provide a measurement unit having the above-described configuration and improving the measurement accuracy and a flow rate measurement device including the measurement unit.

  The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

It is a figure which shows the gas meter provided with the flow measuring device which concerns on Embodiment 1 of this invention. It is a disassembled perspective view which shows the flow measuring device and intermediate flow path part of FIG. It is a perspective view which shows the state which accommodated the flow measuring device of FIG. 2 in the intermediate flow path part. It is a figure which shows the state which accommodated the flow measuring device which concerns on Embodiment 2 of this invention in the intermediate flow path part.

A measurement unit according to a first aspect of the present invention is a measurement unit used in a flow rate measurement device that measures a flow rate of a fluid flowing through a cylindrical measurement flow path unit, and a pair of ultrasonic transmission / reception waves that transmit / receive ultrasonic waves to / from each other. , A substrate that is electrically connected to the ultrasonic transducer, a substrate holding unit that supports the substrate, and a sensor that supports the pair of ultrasonic transducers so that their relative positions are fixed to each other A measurement unit according to a second aspect of the present invention includes a holding member, and a holding member having a locking portion for locking the measurement flow path portion. The measurement circuit further includes a mounted measurement circuit, and the measurement circuit is measured by a propagation time measurement unit that measures a time during which the ultrasonic wave propagates between the pair of ultrasonic transducers and the propagation time measurement unit. Flow rate of the fluid based on time And an arithmetic unit that calculates.

  In the measurement unit according to a third aspect of the present invention, in the first or second aspect, the measurement flow path section is housed in the fluid flow path section, and the inside communicates with the fluid flow path section. The pair of ultrasonic transducers may be disposed between the outer wall of the fluid flow path portion and the outer wall of the measurement flow path portion.

  In the measurement unit according to a fourth aspect of the present invention, in any one of the first to third aspects, the holding member includes a first side portion along the first side plate of the measurement flow path portion, and the measurement flow path. A second side part along the second side plate of the part, and a pair of installation parts protruding outward from at least one side part of the first side part and the second side part, The ultrasonic transducer may be disposed between the side portion and the installation portion.

  In the measurement unit according to a fifth aspect of the present invention, in the fourth aspect, the holding member is along the top plate of the measurement flow path section and is perpendicular to the first side section and the second side section. There may be provided a top, and the substrate may be fixed to the top.

  In the measurement unit according to the sixth aspect of the present invention, in the fifth aspect, the space between the top and the installation portion may be open.

  In the measurement unit according to the seventh aspect of the present invention, in any one of the first to sixth aspects, the pair of ultrasonic transducers may be arranged to face each other across the measurement flow path section. Good.

  The measurement unit according to an eighth aspect of the present invention is the measurement unit according to any one of the first to sixth aspects, further comprising a reflection portion fixed to the holding member, wherein the pair of ultrasonic transducers is the reflection portion. The measurement channel section may be interposed between the two.

  A flow measurement device according to a ninth aspect of the present invention includes the measurement unit according to any one of the first to eighth aspects, and the measurement flow path section.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout all the drawings, and redundant description thereof is omitted.

(Embodiment 1)
(Configuration of gas meter)
FIG. 1 is a diagram schematically showing a gas meter 12 including a flow rate measuring device 10 according to the first embodiment. In addition, although gas is demonstrated as an example of a fluid below, other gas, such as air, and liquids, such as water, can be used as a fluid. The flow rate measuring device that measures the flow rate of a fluid other than gas is the same as the flow rate measuring device 10 that measures the flow rate of gas, and thus the description thereof is omitted.

  As shown in FIG. 1, the gas meter 12 has a substantially rectangular parallelepiped shape, and a display unit 14 is provided on the front surface thereof, for example. The gas meter 12 has an internal space, and a control circuit 16 and a fluid flow path portion 18 are provided in the internal space. The control circuit 16 includes, for example, an integrated circuit (not shown) for wireless communication for transmitting information on the measured gas flow rate by wireless communication, an integrated circuit (not shown) for controlling each component, and A memory (not shown) for storing information is included. The fluid flow path portion 18 is a pipe line that forms a fluid flow path, and includes an inflow pipe portion 20, an intermediate flow path portion 22, and an outflow pipe portion 24. Since the gas flows from the inflow pipe portion 20 through the intermediate flow path portion 22 to the outflow pipe portion 24, the gas is referred to as a relatively upstream side and a downstream side along the gas flow.

  The inflow pipe part 20 includes a columnar internal space (inflow path), and the outflow pipe part 24 includes a columnar internal space (outflow path). The inflow path of the inflow pipe section 20 and the outflow path of the outflow pipe section 24 extend parallel to each other in the internal space of the main body of the gas meter 12. The upstream end of the inflow pipe part 20 and the downstream end of the outflow pipe part 24 are cylindrical and protrude upward from the main body. The inflow pipe part 20 has an upstream end connected to a gas pipe (not shown) connected to a gas supply source, and a downstream end connected to an inlet of the intermediate flow path part 22. The outflow pipe portion 24 has a downstream end connected to a gas pipe (not shown) connected to a gas consumer, and an upstream end connected to an outlet of the intermediate flow path portion 22. A gap between the downstream end of the inflow pipe portion 20 and the intermediate flow path portion 22 and a gap between the upstream end of the outflow pipe portion 24 and the intermediate flow path portion 22 are blocked by the filler 58. ing.

  The intermediate flow path part 22 is formed, for example with metals, such as aluminum. The intermediate flow path part 22 is a container shape with an open top surface and has an internal space (intermediate flow path). Of this opening, a region (inlet) surrounded by the upstream wall 22 a of the intermediate flow path portion 22 and the like faces the opening at the downstream end of the inflow pipe portion 20. In addition, a region (outlet) surrounded by the downstream wall 22 b of the intermediate flow path portion 22 in the opening faces the opening at the upstream end of the outflow pipe portion 24. Thereby, the intermediate flow path of the intermediate flow path section 22, the inflow path of the inflow pipe section 20, and the outflow path of the outflow pipe section 24 communicate with each other to form a fluid flow path. The measurement flow path portion 26 of the flow rate measuring device 10 is accommodated in the intermediate flow path (fluid flow path) of the intermediate flow path portion 22.

  The measurement flow path portion 26 is a hollow member that is open at both ends, and its internal space is used as a measurement flow path. In the present embodiment, the measurement flow path portion 26 is configured by a cylindrical member having a rectangular cross section. The length dimension of the measurement flow path portion 26 is smaller than the length dimension of the intermediate flow path portion 22. Therefore, a gap is formed between the upstream end of the measurement flow path portion 26 and the upstream wall 22a of the intermediate flow path portion 22 and between the downstream end of the measurement flow path portion 26 and the downstream wall 22b of the intermediate flow path portion 22. Are provided. The measurement channel of the measurement channel unit 26 communicates with the fluid channel of the intermediate channel unit 22 through this gap.

  A plurality of (in this embodiment, five) rectifying plates 28 are arranged inside the measurement flow path portion 26. The rectifying plate 28 extends along the axis of the measurement flow path portion 26 in parallel with the top plate 26 a and the bottom plate 26 b of the measurement flow path portion 26. The measurement channel of the measurement channel unit 26 is partitioned in parallel by the rectifying plate 28.

  Two first ribs 30 a and 30 b are provided on the outer surface of the top plate 26 a of the measurement flow path section 26, and the gas flow direction of the measurement flow path along the axis of the measurement flow path section 26 (hereinafter, “left-right direction”). ) Are provided at intervals. In addition, two second ribs 32 a and 32 b are provided on the outer surface of the bottom plate 26 b of the measurement flow path portion 26 with an interval in the left-right direction. Of the two first ribs 30a, 30b, the first rib (upstream first rib) 30a on the upstream side, and between the two second ribs 32a, 32b, the second rib (upstream second rib) on the upstream side. ) 32a is also provided in the left-right direction. A gap is also provided in the left-right direction between the first rib (downstream first rib) 30b on the downstream side and the second rib (downstream second rib) 32b on the downstream side. In these gaps, annular sealing materials 34a and 34b are arranged.

  The pair of sealing materials 34 a and 34 b are attached to the measurement flow path portion 26 with a space in the left-right direction. A sealing material (upstream sealing material) 34a on the upstream end side of the measurement flow path portion 26 is disposed in a gap between the upstream first rib 30a and the upstream second rib 32a. A sealing material (downstream sealing material) 34b on the downstream end side of the measurement flow path portion 26 is disposed in a gap between the downstream first rib 30b and the downstream second rib 32b.

  The sealing materials 34 a and 34 b are wound around the measurement flow path unit 26 in a direction perpendicular to the axis of the measurement flow path unit 26, and are provided around the outer periphery of the measurement flow path unit 26. The thickness dimension of the sealing materials 34 a and 34 b is set to be equal to or larger than the gap dimension between the inner surface of the fluid flow path portion 18 and the outer surface of the measurement flow path portion 26. As this clearance, for example, a clearance between the top plate 26a of the measurement flow path portion 26 and the downstream end of the inflow pipe portion 20 facing this, or the outflow facing the top plate 26a of the measurement flow path portion 26 and this. Examples include a gap between the upstream end of the pipe part 24 and a gap between the bottom part 22e of the intermediate flow path part 22 and the bottom plate 26b of the measurement flow path part 26.

  The sealing materials 34a and 34b close the gap between the inner surface of the fluid flow path portion 18 and the outer surface of the measurement flow path portion 26, thereby blocking the gas flow. For this reason, the fluid flow path of the fluid flow path section 18 and the measurement flow path of the measurement flow path section 26 are connected while maintaining airtightness, and the gas flowing through the fluid flow path passes through the measurement flow path. That is, all of the gas flowing through the inflow pipe portion 20 flows out to the outflow pipe portion 24 through the measurement flow passage portion 26 without going to the outflow pipe portion 24 through the outside of the measurement flow passage portion 26.

  The holding member 70 and the substrate 36 attached to the holding member 70 are disposed on the outer surface of the top plate 26a of the measurement flow path section 26 between the pair of sealing materials 34a and 34b. Between the pair of sealing materials 34 a and 34 b, the top plate 26 a is exposed from the opening of the intermediate flow path portion 22, and the holding member 70 and the substrate 36 are disposed here. In this exposed range, the gap between the fluid flow path portion 18 and the measurement flow path portion 26 is closed by the sealing materials 34a and 34b. Therefore, the gas in the fluid channel of the fluid channel unit 18 does not flow on the substrate 36 beyond the sealing material 34a on the outer surface of the top plate 26a.

(Configuration of flow measurement device)
FIG. 2 is an exploded perspective view showing the flow rate measuring device 10 and the intermediate flow path portion 22. With reference to this FIG. 2, the structure of the flow volume measuring apparatus 10 is demonstrated in detail. As shown in FIG. 2, the flow rate measuring device 10 includes a measurement flow path portion 26, a measurement unit 35, and sealing materials 34 a and 34 b. The measurement unit 35 includes a holding member 70, a substrate 36, and a pair of ultrasonic transducers 38.

  The measurement flow path section 26 has a cylindrical outer wall, and the outer wall is constituted by a top plate 26a, a bottom plate 26b facing the top plate 26a, and a first side plate 26c and a second side plate 26d perpendicular to them. . The pair of first ribs 30a, 30b provided on the top plate 26a and the pair of second ribs 32a, 32b provided on the bottom plate 26b extend in parallel in the front-rear direction. Moreover, the convex part 31 is provided in the top plate 26a. The convex portion 31 extends perpendicularly to the downstream first rib 30b, and its downstream end is connected to the center of the downstream first rib 30b. The front-rear direction is a direction perpendicular to the left-right direction and the side plates 26c, 26d.

  In the gap between the upstream first rib 30a and the upstream second rib 32a, a groove (upstream groove) 40a extending in the vertical direction is provided in each of the side plates 26c, 26d of the measurement flow path section 26. Also, in the gap between the downstream first rib 30b and the downstream second rib 32b, a groove (downstream groove) 40b extending in the vertical direction is provided in each side plate 26c, 26d of the measurement flow path portion 26. . The width dimension of these grooves 40a and 40b is set equal to the width dimension of the sealing materials 34a and 34b. Note that the up-down direction is a direction perpendicular to the left-right direction and the front-rear direction.

  The sealing materials 34a and 34b are, for example, annular members having elasticity, and O-rings or the like are used. In addition, the sealing materials 34a and 34b should just fill between the outer wall of the fluid flow-path part 18 and the outer wall of the measurement flow-path part 26, and are not restricted to an O-ring. For example, as the sealing materials 34a and 34b, a fixed sealing material other than O-ring, a paste-like amorphous sealing material, and the like can be used.

  Openings 42 a and 42 b are provided in the side plates 26 c and 26 d of the measurement flow path portion 26. One opening (upstream opening) 42a is disposed downstream of the upstream groove 40a and is located closer to the upstream groove 40a than the downstream groove 40b. The other opening part (downstream opening part) 42b shown with a dashed line is distribute | arranged upstream from the downstream groove | channel 40b, and is located near the downstream groove | channel 40b rather than the upstream groove | channel 40a. The openings 42 a and 42 b penetrate the side plates 26 c and 26 d and are covered with the ultrasonic transmission film 44. The ultrasonic transmission film 44 is a film that transmits ultrasonic waves and suppresses the passage of gas. For example, a mesh or the like is used. However, the openings 42 a and 42 b may not be covered with the ultrasonic transmission film 44.

  The holding member 70 is a member that attaches the substrate 36 and the ultrasonic transducer 38 to the measurement flow path portion 26, and includes an attachment portion 72 and a pair of installation portions 74a and 74b. The attachment portion 72 is a locking portion for locking the measurement flow path portion 26, and is disposed between, for example, the first side portion 72a, the second side portion 72b, and the side portions 72a and 72b. The top portion 72c is provided. Each of the top part 72c and the side parts 72a, 72b is a rectangular flat plate, and the side parts 72a, 72b extend perpendicularly to the top part 72c from each side end of the top part 72c. Due to the top portion 72c and the side portions 72a and 72b, the attachment portion 72 has a rectangular parallelepiped internal space with a rectangular cross section, and has a shape in which the bottom surface and both ends in the left-right direction are open.

  The top portion 72c is a substrate holding portion that supports the substrate 36, and a protrusion 46 is provided on the outer surface of the top portion 72c. The protrusion 46 is used as a positioning portion of the substrate 36 with respect to the holding member 70. In this embodiment, three columnar protrusions 46 protrude from the top portion 72c and are disposed between the pair of first ribs 30a and 30b.

  The length dimension of the top portion 72c is set equal to the distance dimension between the pair of first ribs 30a and 30b. A notch 73 is provided at one end (downstream end) of the top portion 72c, and the notch 73 extends vertically from the downstream end of the top portion 72c to the downstream end. The notch 73 is set to a dimension that the convex portion 31 of the measurement flow path portion 26 fits. The distance between the inner surfaces of the first side portion 72a and the second side portion 72b is set substantially equal to the distance between the outer surfaces of the side plates 26c and 26d of the measurement flow path portion 26.

  The lateral dimension of the side parts 72a and 72b is set equal to or smaller than the lateral dimension of the top part 72c. The vertical dimension of the side parts 72 a and 72 b is set equal to or smaller than the vertical dimension of the measurement flow path part 26. Holes (entrances) 78a and 78b are opened in the respective side portions 72a and 72b. One doorway (upstream side doorway) 78a is arranged near the other end (upstream end) of the top portion 72c, and the other doorway (downstream side doorway) 78b is arranged near the downstream end of the top portion 72c.

  The installation parts 74a and 74b are sensor holding parts that support the pair of ultrasonic transducers 38 so that their relative positions are fixed to each other. The installation parts 74a and 74b are provided so as to surround the doorways 78a and 78b of the side parts 72a and 72b, and have an installation surface part 75 and a connection part 76, for example. The installation surface part 75 of one installation part (upstream installation part) 74a is arranged on the upstream end side of the top part 72c, and the installation surface part 75 of the other installation part (downstream installation part) 74b is the downstream end side of the top part 72c. It is arranged in.

  The installation surface portion 75 of the upstream installation portion 74a and the installation surface portion 75 of the downstream installation portion 74b face each other in parallel. One end of the installation surface portion 75 and one end of the connection portion 76 are joined to the side portions 72a and 72b, respectively, and the other end of the installation surface portion 75 and the other end of the connection portion 76 are joined. Thereby, the installation parts 74a and 74b protrude in the V shape from the side parts 72a and 72b, and the triangular columnar internal space (installation space) is formed between the side parts 72a and 72b.

  The space between the installation portions 74a and 74b and the top portion 72c (the upper portion of the installation portions 74a and 74b) is open, and the top surface side opening 80 surrounded by the installation surface portion 75, the connection portion 76, and the top portion 72c. Is formed. The installation space communicates with the outside from the top surface side opening 80 and communicates with the internal space of the attachment portion 72 through the entrances 78a and 78b. Grooves (installation grooves) 77 are provided in the vicinity of the installation surface portion 75 of the connecting portion 76 and in the vicinity of the installation surface portion 75 of the side portions 72a and 72b. The dimension between the pair of installation grooves 77 is equal to the width dimension parallel to the radiation surface of the ultrasonic transducer 38, and the shape of the installation groove 77 is formed along the end face shape of the ultrasonic transducer 38. Yes.

  The substrate 36 is a thin plate-like body and has a quadrangular shape. The dimension in the front-rear direction of the substrate 36 is set to be substantially the same as the dimension in the front-rear direction of the top portion 72 c of the holding member 70. The horizontal dimension of the substrate 36 is set to be smaller than the dimension between the upstream first rib 30a and the convex portion 31. Components such as electronic components and circuit elements are mounted on the surface of the substrate 36. The components include a terminal 48 for connection to the control circuit 16 (FIG. 1) of the gas meter 12 (FIG. 1) and an integrated circuit (measurement circuit) 50 having a measurement function of the ultrasonic transducer 38. .

  The measurement circuit 50 has a propagation time measurement unit and a calculation unit. The propagation time measurement unit measures the time during which the ultrasonic wave propagates between the pair of ultrasonic transducers 38. The computing unit calculates the gas flow rate based on the time measured by the propagation time measuring unit. The propagation time measurement unit and the calculation unit are realized by a program stored in the measurement circuit 50, for example. Note that the measurement circuit may be configured by one circuit having the functions of the propagation time measurement unit and the calculation unit, or two circuits individually having the function of the transport time measurement unit and the function of the calculation unit.

  For example, three holes (fixed holes) 52 are opened in the substrate 36, and these fixed holes 52 are used to fix the substrate 36 to the attachment portion 72 of the holding member 70. The inner diameter dimension of the fixing hole 52 is larger than the outer dimension of the protrusion 46 of the measurement flow path portion 26, and the protrusion 46 can be inserted into the fixing hole 52. By fitting the protrusions 46 into the fixing holes 52, the substrate 36 is disposed so as to be accommodated in the attachment portion 72.

  The ultrasonic transducer 38 includes a piezoelectric body (not shown), an acoustic matching body (not shown), and a terminal (not shown). A piezoelectric body is an element that expands and contracts in the thickness direction when a voltage is applied, thereby converting electrical vibration into mechanical vibration.

  The acoustic matching body has a radiation surface that radiates mechanical vibration generated by the piezoelectric body to the gas as ultrasonic waves. The acoustic matching body is an element that matches the acoustic impedance of the piezoelectric body and the acoustic impedance of the gas in order to emit ultrasonic waves from the radiation surface. Lead pins 56 are connected to terminals connected to the piezoelectric body. The ultrasonic transducer 38 is electrically connected to the substrate 36 by soldering the lead pins 56 and the wiring on the substrate 36. Note that the ultrasonic transducer 38 and the substrate 36 may be electrically connected by a lead wire or the like instead of the lead pin 56.

  The intermediate flow path portion 22 has a substantially rectangular parallelepiped outer wall having an open top surface, and the outer wall includes an upstream wall 22a and a downstream wall 22b that are opposed to each other in a gas flow direction, and a gas flow direction. It is comprised by a pair of side wall 22c, 22d opposingly arranged in the direction orthogonal to the bottom part 22e. A filler 58 is provided at each opening side end of the upstream wall 22a, the downstream wall 22b, and the side walls 22c, 22d, and the filler 58 continuously surrounds the periphery of the opening of the intermediate flow path portion 22.

  The side walls 22c and 22d are provided with extended portions 60a and 60b, part of which protrudes outward. The extended portions 60a and 60b form a triangular prism-shaped internal space (expanded space), and a part of the substantially rectangular parallelepiped-shaped fluid flow channel of the intermediate flow channel portion 22 is expanded by the expanded space. The extended portion (upstream side extended portion) 60a of the side wall 22c is provided on the downstream side of the upstream first rib 30a, and more upstream than the downstream side first rib 30b than the extended portion (downstream side extended portion) 60b of the side wall 22d. Is provided. The expansion portions 60a and 60b are formed so that the installation portions 74a and 74b of the holding member 70 are accommodated in the expansion space.

  In the intermediate flow path portion 22, a recess (upstream recess) 62a is provided upstream of the upstream extension 60a, and a recess (downstream recess) 62b is provided downstream of the downstream extension 60b. ing. The width of the fluid flow path of the intermediate flow path portion 22 is narrowed by these hollow portions 62a and 62b, and the width dimension is set to be substantially the same as the width dimension of the measurement flow path portion 26 fitted with the sealing materials 34a and 34b. Has been. Moreover, the dimension between the upstream dent part 62a and the downstream dent part 62b is set to be the same as the dimension between the upstream groove 40a and the downstream groove 40b. Note that the filler 58 may be provided on the recessed portions 62a and 62b.

(Assembly of flow measuring device)
FIG. 3 is a diagram illustrating a state in which the flow rate measuring device 10 including the measurement unit 35 is housed in the intermediate flow path portion 22. Hereinafter, the assembly of the flow rate measuring device 10 will be described with reference to FIGS. However, the order of assembling the measuring unit 35 and the flow rate measuring device 10 is not limited to the following order.

  As shown in FIG. 2, first, the ultrasonic transducer 38 is installed on the holding member 70. At this time, the ultrasonic transducer 38 is inserted into the installation space of the installation portions 74 a and 74 b from the top surface side opening 80 so that the end of the ultrasonic transducer 38 fits in the installation groove 77. Thereby, the radiation surface of the ultrasonic transducer 38 faces the entrances 78a and 78b, and the ultrasonic transducer 38 is fixed to a predetermined position of the holding member 70 at a predetermined angle.

  Next, the substrate 36 is mounted on the top portion 72 c of the holding member 70 while the protrusion 46 of the holding member 70 is inserted into the fixing hole 52 of the substrate 36. Thereby, the substrate 36 is disposed at a predetermined position of the holding member 70. Then, the lead pins 56 of the ultrasonic transducer 38 are soldered to the wiring of the substrate 36, and the ultrasonic transducer 38 is electrically connected to the substrate 36.

  Then, the sealing materials 34 a and 34 b are fitted into the grooves 40 a and 40 b of the measurement flow path portion 26, and the holding member 70 is attached to the measurement flow path portion 26. At this time, the upstream end of the top portion 72 c is applied to the upstream first rib 30 a, the downstream end of the top portion 72 c is applied to the downstream first rib 30 b, and the convex portion 31 is fitted into the notch 73. Accordingly, the top portion 72c is along the top plate 26a, the first side portion 72a is along the first side plate 26c, and the second side portion 72b is along the second side plate 26d. For this reason, the holding member 70, the substrate 36 attached thereto, and the ultrasonic transducer 38 are fixed at predetermined positions of the measurement flow path portion 26.

  That is, the holding member 70 is arranged such that the upstream side entrance 78a corresponds to the upstream side opening 42a of the measurement flow path portion 26 and the downstream side entrance 78b corresponds to the downstream side opening 42b. Further, the ultrasonic transducer 38 is disposed so that the path of the ultrasonic wave radiated from the radiation surface thereof is inclined at a predetermined angle with respect to the axis of the measurement flow path portion 26 through the openings 42a and 42b. The Accordingly, the pair of ultrasonic transducers 38 are arranged so as to transmit and receive ultrasonic waves to each other. The substrate 36 is disposed between the pair of sealing materials 34a and 34b.

  Subsequently, the measurement flow path portion 26 is accommodated in the intermediate flow path portion 22 so that the sealing materials 34 a and 34 b correspond to the recess portions 62 a and 62 b of the intermediate flow path portion 22. As a result, as shown in FIG. 3, the sealing materials 34 a and 34 b are in close contact with the outer surface of the measurement channel portion 26 and the inner surface of the intermediate channel portion 22, and the intermediate plates and the side plates 26 c and 26 d of the measurement channel portion 26. The gap between the recesses 62a and 62b of the path portion 22 and the gap between the bottom plate 26b (FIG. 2) of the measurement flow path portion 26 and the bottom portion 22e (FIG. 2) of the intermediate flow path portion 22 are closed. With the sealing materials 34a and 34b, the measurement flow path section 26 and the intermediate flow path section 22 are hermetically partitioned into three spaces except for the top plate 26a side of the measurement flow path section 26.

  Specifically, the first is a fluid flow path (upstream intermediate flow path) between the upstream depression 62a and the upstream wall 22a. The second is a fluid flow path (downstream intermediate flow path) between the downstream depression 62b and the downstream wall 22b. The third is a fluid flow path (central intermediate flow path) between the upstream depression 62a and the downstream depression 62b. The central intermediate flow path is blocked from the upstream intermediate flow path and the downstream intermediate flow path by the sealing materials 34a and 34b.

  Further, between the upstream end of the measurement flow path portion 26 and the upstream wall 22a of the intermediate flow path portion 22, and between the downstream end of the measurement flow path portion 26 and the downstream wall 22b of the intermediate flow path portion 22, Each is provided with an interval. Thereby, the upstream intermediate flow path communicates with the measurement flow path of the measurement flow path section 26 through the opening at the upstream end of the measurement flow path section 26. The downstream intermediate flow path communicates with the measurement flow path of the measurement flow path section 26 through the opening at the downstream end of the measurement flow path section 26.

  Further, the installation portions 74a and 74b of the holding member 70 are accommodated in the expansion spaces of the expansion portions 60a and 60b. The substrate 36 is disposed in the central intermediate flow path of the intermediate flow path portion 22.

  Subsequently, as shown in FIG. 1, the intermediate flow path portion 22 in which the measurement flow path portion 26 is stored is stored in the internal space of the gas meter 12. At this time, the sealing materials 34a and 34b of the measurement flow path section 26 and the filler 58 of the intermediate flow path section 22 are in close contact with the downstream end of the inflow pipe section 20 and the upstream end of the outflow pipe section 24, respectively. The flow path part 22 is disposed. Thereby, the inflow path of the inflow pipe part 20 and the upstream intermediate flow path of the intermediate flow path part 22 are connected, and the outflow path of the outflow pipe part 24 and the downstream intermediate flow path of the intermediate flow path part 22 are connected. . Furthermore, since the upstream intermediate flow path and the downstream intermediate flow path communicate with the measurement flow path, the inflow path, the upstream intermediate flow path, the measurement flow path, the downstream intermediate flow path, and the outflow path are in this order. Connected to form one U-shaped channel.

  At this time, since the substrate 36 is disposed on the outer surface of the measurement flow path section 26 between the inflow pipe section 20 and the outflow pipe section 24, it appears in the internal space of the gas meter 12. Therefore, the terminal 48 on the substrate 36 is connected to the control circuit 16 by a lead wire or the like, and the flow rate measuring device 10 is incorporated into the gas meter 12.

(Operation of flow measurement device)
When measuring the flow rate of the gas flowing through the fluid flow path, the gas pipe is connected to each of the inflow pipe section 20 and the outflow pipe section 24. Thus, the gas is supplied from the gas pipe, flows through the inflow path of the inflow pipe portion 20, and flows into the upstream intermediate flow path of the intermediate flow path portion 22. Then, the gas flows from the upstream intermediate flow channel through the opening at the upstream end of the measurement flow channel portion 26, passes through the measurement flow channel, and downstream through the opening at the downstream end of the measurement flow channel portion 26. It flows to the side intermediate flow path. Further, the gas enters the outflow path of the outflow pipe section 24 from the downstream intermediate flow path and flows to the gas pipe.

  In a state where the gas flows through the measurement flow path, for example, when the measurement circuit 50 sends an electrical signal to the upstream ultrasonic transducer 38, the ultrasonic transducer 38 converts the electrical signal into an ultrasonic wave. And radiate from the radiation surface. As a result, the ultrasonic wave passes through the upstream opening 42a and enters the measurement channel, crosses the measurement channel obliquely, exits from the downstream opening 42b, and reaches the ultrasonic transducer 38 on the downstream side. . The ultrasonic transducer 38 on the downstream side receives the ultrasonic wave, converts it into electric vibration, and outputs it to the measurement circuit 50.

  In the measurement circuit 50, the difference between the time when the propagation time measurement unit outputs the electrical signal to the upstream ultrasonic transducer 38 and the time when the electrical signal is input from the downstream ultrasonic transducer 38 is calculated. Based on this, the propagation time of the ultrasonic wave is obtained. Similarly, ultrasonic waves are radiated from the downstream ultrasonic transducer 38, and the upstream ultrasonic transducer 38 receives the ultrasonic waves. Then, the propagation time measurement unit obtains the propagation time of this ultrasonic wave. Finally, the calculation unit calculates the gas flow rate based on the propagation time obtained by the propagation time measurement unit, and the measurement circuit 50 outputs the gas flow rate to the control circuit 16. The control circuit 16 stores information on the acquired gas flow rate in a memory, displays the information on the display unit 14, and transmits the information to the outside using a wireless circuit and an antenna.

(Function, effect)
According to the above configuration, since the holding member 70 serves as the holding member for the substrate 36 and the holding member for the ultrasonic transducer 38, the flow measuring device 10 can be reduced in size and cost. Moreover, since the board | substrate 36 and the ultrasonic transducer 38 are installed in the holding member 70, shortening of the distance between these is achieved. Therefore, generation of noise during this period can be reduced, and the measurement accuracy of the flow rate measuring device 10 can be improved.

  Further, since the top surface side opening 80 is provided in the holding member 70, the ultrasonic transducer 38 can be easily inserted from the top surface side opening 80 into the installation spaces of the installation portions 74a and 74b. Further, by providing the installation groove 77 in the holding member 70, the ultrasonic transducer 38 can be easily attached to the holding member 70, and the workability is excellent. Moreover, the pair of ultrasonic transducers 38 attached to the holding member 70 has a predetermined separation distance and a predetermined direction. For this reason, when attaching the ultrasonic transducer 38 to the holding member 70, it is not necessary to adjust the position and orientation of the ultrasonic transducer 38, and the workability is further improved. In addition, an error in the relative position of the pair of ultrasonic transducers 38 is suppressed, and a decrease in measurement accuracy of the flow rate measuring device 10 due to the error can be suppressed.

  Further, the holding member 70, the substrate 36, and the ultrasonic transducer 38 are integrated into a unit in advance. Therefore, when inspecting the quality of the measurement unit 35 or the flow rate measurement device 10 in which the measurement unit 35 is mounted on the measurement flow path unit 26, the measurement unit 35 or the flow rate measurement device 10 can be individually inspected. . As a result, the measurement unit 35 or the flow rate measuring device 10 can be inspected in an environment suitable for quality inspection, and the inspection accuracy can be improved and simplified. Furthermore, before the measurement unit 35 or the flow rate measuring device 10 is incorporated in the gas meter 12, they can be inspected to detect defective products at an early stage.

  Further, a substrate 36 is disposed between the pair of sealing materials 34a and 34b. Therefore, almost no gas flows on the substrate 36 or the measurement circuit 50 mounted on the substrate 36, and the occurrence of problems due to the gas flow can be suppressed.

  Further, the substrate 36 is exposed to the internal space of the gas meter 12 from the opening of the intermediate flow path portion 22 between the inflow pipe portion 20 and the outflow pipe portion 24. For this reason, the board | substrate 36 and the control circuit 16 in the gas meter 12 can be connected easily.

  Furthermore, since the vibration from the outside is blocked by the metal intermediate flow path portion 22, it is possible to suppress the measurement accuracy of the flow rate measuring device 10 from being reduced by noise due to the external vibration.

(Embodiment 2)
FIG. 4 is a diagram illustrating a state in which the flow rate measuring device 10 including the measurement unit 35 according to the second embodiment is housed in the intermediate flow path portion 22. As shown in FIG. 4, in the flow rate measuring device 10 according to the second embodiment, a pair of ultrasonic transducers 38 are arranged so as to sandwich the measurement flow path portion 26 between the reflection surface 64a.

  Two extended portions 60a and 60b are provided on one side wall 22d of the intermediate flow path portion 22 so as to be spaced apart from each other. These extended portions 60a and 60b are disposed between the upstream dent portion 62a and the downstream dent portion 62b.

  An upstream opening 42a and a downstream opening 42b are provided on the second side plate 26d of the measurement flow path portion 26 side by side in the left-right direction. One opening (intermediate opening) 42c is provided in the first side plate 26c. The intermediate opening 42c is disposed between the upstream opening 42a and the downstream opening 42b.

  In the holding member 70, an upstream side entrance 78a and a downstream side entrance 78b are opened in the second side portion 72b, and a hole (intermediate port) is provided in the first side portion 72a. The upstream side installation portion 74a is provided on the second side portion 72b so as to surround the upstream side entrance 78a, and the downstream side installation portion 74b is provided on the second side portion 72b so as to surround the downstream side entrance 78b. The intermediate port is disposed between the upstream side entrance 78a and the downstream side entrance 78b. The intermediate port may penetrate the first side portion 72a or may be recessed from the inner surface of the first side portion 72a. The reflection portion 64 is fixed to the intermediate port, and the reflection surface 64a of the reflection portion 64 is disposed on the inner surface side of the first side portion 72a.

  When the flow measuring device 10 is assembled, the ultrasonic transducer 38 and the substrate 36 are attached to the holding member 70, and the lead pins 56 of the ultrasonic transducer 38 are soldered to the wiring of the substrate 36. Further, the sealing materials 34 a and 34 b and the holding member 70 are attached to the measurement flow path portion 26. Accordingly, the holding member 70 is disposed such that the upstream side entrance 78a corresponds to the upstream side opening 42a, the downstream side entrance 78b corresponds to the downstream side opening 42b, and the intermediate port corresponds to the intermediate opening 42c. The Each ultrasonic transducer 38 sandwiches the measurement flow path portion 26 between the reflection surface 64a, and the ultrasonic path passes through the respective ports 78a, 78b, and 78c, and is predetermined with respect to the axis of the measurement flow path portion 26. It is arranged so as to be inclined at an angle formed. The reflection unit 64 is disposed so as to be located at the intersection of the ultrasonic path of the upstream ultrasonic transducer 38 and the ultrasonic path of the downstream ultrasonic transducer 38.

  Subsequently, the measurement flow path portion 26 is accommodated in the intermediate flow path portion 22 so that the sealing materials 34a and 34b correspond to the recessed portions 62a and 62b. Thereby, the installation portions 74a and 74b of the holding member 70 are accommodated in the expansion space surrounded by the expansion portions 60a and 60b, and the ultrasonic transducer 38 fixed to the installation portions 74a and 74b is arranged in the expansion space. The reflection part 64 fixed to the installation parts 74 a and 74 b is disposed between the first side plate 26 c of the measurement flow path part 26 and the side wall 22 c of the intermediate flow path part 22. Finally, the intermediate flow path portion 22 in which the measurement flow path portion 26 is accommodated is accommodated in the internal space of the gas meter 12, and the terminal 48 on the substrate 36 is connected to the control circuit 16 by a lead wire or the like. 10 is incorporated into the gas meter 12.

  When the flow rate of the gas flowing through the fluid flow path is measured by the flow rate measuring device 10, for example, when the measurement circuit 50 sends an electrical signal to the ultrasonic transducer 38 on the upstream side, the ultrasonic transducer 38 receives the electrical signal. Is converted into ultrasonic waves and emitted from the radiation surface. The ultrasonic wave passes through the upstream opening 42a and enters the measurement channel, crosses the measurement channel obliquely, passes through the opening 42c, and reaches the reflection surface 64a. Then, the ultrasonic wave is reflected by the reflecting surface 64a, passes again through the opening 42c, enters the measurement channel, crosses the measurement channel diagonally, exits from the downstream side opening 42b, and then enters the downstream side. It reaches the sonic transducer 38. The ultrasonic transducer 38 on the downstream side receives the ultrasonic wave, converts it into electric vibration, and outputs it to the measurement circuit 50.

  In the measurement circuit 50, the difference between the time when the propagation time measurement unit outputs the electrical signal to the upstream ultrasonic transducer 38 and the time when the electrical signal is input from the downstream ultrasonic transducer 38 is calculated. Based on this, the propagation time of the ultrasonic wave is obtained. Similarly, ultrasonic waves are radiated from the downstream ultrasonic transducer 38, and the upstream ultrasonic transducer 38 receives the ultrasonic waves. Then, the propagation time measurement unit obtains the propagation time of this ultrasonic wave. Finally, the calculation unit calculates the gas flow rate based on the propagation time obtained by the propagation time measurement unit.

(Other embodiments)
In the flow rate measuring apparatus 10 according to the first embodiment, a “Z method” configuration is adopted in which a pair of ultrasonic transducers 38 are arranged to face each other. Further, in the flow rate measuring device 10 according to the second embodiment, a “V” configuration in which one reflecting surface 64 a is disposed between the pair of ultrasonic transducers 38 is employed. On the other hand, the structure of another system can be adopted. For example, a “W” type configuration in which three reflecting surfaces 64 a are disposed between a pair of ultrasonic transducers 38 may be employed.

  In the flow rate measuring device 10 according to all the above-described embodiments, the substrate 36 is disposed so as to fit on the attachment portion 72 of the holding member 70. However, as long as the substrate 36 fits between the pair of sealing materials 34a and 34b in the intermediate flow path portion 22, the size and arrangement of the substrate 36 are not limited thereto. For example, you may arrange | position the board | substrate 36 on the attaching part 72 of the holding member 70, and the installation parts 74a and 74b.

  In the flow rate measuring apparatus 10 according to all the above embodiments, the substrate 36 is attached to the holding member 70 by inserting the protrusion 46 of the holding member 70 into the fixing hole 52 of the substrate 36, but the attachment method is limited to this. Not. For example, the substrate 36 can be fixed to the holding member 70 with screws or rails.

  In the flow measurement device 10 according to all the above embodiments, the holding member 70 is positioned with respect to the measurement flow path portion 26 by the first ribs 30a and 30b, the convex portion 31, and the notch 73. However, the positioning of the holding member 70 is not limited to this.

  For example, only the first ribs 30 a and 30 b may be used for positioning the holding member 70 without providing the convex portion 31 and the notch 73.

  Further, a protrusion may be provided in the measurement flow path portion 26, a hole may be provided in the holding member 70, and the protrusion and the hole may be used for positioning. In this case, the holding member 70 can be disposed at a predetermined position of the measurement flow path portion 26 by inserting the protrusion into the hole.

  Furthermore, the extended portions 60 a and 60 b of the intermediate flow path portion 22 and the installation portions 74 a and 74 b of the holding member 70 can be used for positioning the holding member 70. In this case, the holding member 70 is attached to the measurement flow path portion 26 housed in the intermediate flow path portion 22 so that the installation portions 74a and 74b fit into the expansion spaces of the expansion portions 60a and 60b. Thereby, the holding member 70 can be positioned with respect to the measurement flow path portion 26 via the intermediate flow path portion 22.

  In the flow rate measuring apparatus 10 according to all the above embodiments, the entire top surface of the intermediate flow path portion 22 is open. On the other hand, a part of the top surface of the intermediate flow path portion 22 may be opened.

  For example, the opening of the intermediate flow path portion 22 is covered with a lid, and an inflow port facing the inflow tube portion 20 and an outflow port facing the outflow tube portion 24 are provided on the lid. In this case, the dimension between the lid and the top plate 26 a of the measurement channel part 26 accommodated in the intermediate channel part 22 is based on the total dimension of the thickness of the top part 72 c of the holding member 70 and the thickness of the substrate 36. It is set large. For this reason, the board | substrate 36 is fixed via the holding member 70 on the top plate 26a of the measurement flow path part 26, and the board | substrate 36 is covered with a lid | cover. Further, the sealing materials 34a and 34b close the gap between the lid and the measurement flow path portion 26, and the substrate 36 is disposed between the pair of sealing materials 34a and 34b. For this reason, the gas is prevented from flowing on the substrate 36 by the sealing materials 34a and 34b, and the occurrence of the malfunction of the substrate 36 due to the gas is suppressed.

  Note that all the above embodiments may be combined with each other as long as they do not exclude each other.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The measurement unit 35 of the present invention and the flow rate measurement device 10 including the measurement unit 35 are useful as a measurement unit that improves measurement accuracy, a flow rate measurement device including the measurement unit, and the like.

DESCRIPTION OF SYMBOLS 10 Flow measuring device 18 Fluid flow path part 26 Measurement flow path part 26a Top plate 26c 1st side board 26d 2nd side board 35 Measurement unit 36 Substrate 38 Ultrasonic transducer 50 Measurement circuit 64 Reflection part 70 Holding member 72a 1st side part 72b 2nd side part 72c Top part (board | substrate holding | maintenance part)
74a, 74b Installation part (sensor holding part)
80 Top side opening

Claims (9)

A measurement unit used in a flow rate measurement device for measuring a flow rate of a fluid flowing through a cylindrical measurement flow path unit,
A pair of ultrasonic transducers that transmit and receive ultrasonic waves to and from each other;
A substrate electrically connected to the ultrasonic transducer;
A substrate holding portion for supporting the substrate, a sensor holding portion for supporting the pair of ultrasonic transducers so that their relative positions are fixed to each other, and a locking portion for locking the measurement flow path portion, And a holding member having a measuring unit. Further comprising a measurement circuit mounted on the substrate,
The measurement circuit measures a flow time of the fluid based on a time measured by the propagation time measurement unit and a propagation time measurement unit that measures a time during which the ultrasonic wave propagates between the pair of ultrasonic transducers. The measurement unit according to claim 1, further comprising: a calculation unit that calculates. The measurement channel part is housed in the fluid channel part, and the inside communicates with the fluid channel part,
3. The measurement unit according to claim 1, wherein the pair of ultrasonic transducers is disposed between an outer wall of the fluid flow path section and an outer wall of the measurement flow path section. The holding member includes a first side portion along the first side plate of the measurement channel portion, a second side portion along the second side plate of the measurement channel portion, and the first side portion and the second side. Having a pair of installation portions protruding outward from at least one of the side portions;
The measurement unit according to claim 1, wherein the ultrasonic transducer is arranged between the side portion and the installation portion. The holding member has a top portion that is perpendicular to the first side portion and the second side portion along the top plate of the measurement flow path portion,
The measurement unit according to claim 4, wherein the substrate is fixed to the top.   The measurement unit according to claim 5, wherein an opening is provided between the top portion and the installation portion.   The measurement unit according to any one of claims 1 to 6, wherein a pair of the ultrasonic transducers are arranged to face each other with the measurement flow path portion interposed therebetween. A reflection portion fixed to the holding member;
The measurement unit according to any one of claims 1 to 6, wherein a pair of the ultrasonic transducers are arranged with the measurement flow path portion sandwiched between the reflection portion. A measuring unit according to any one of claims 1 to 8,
A flow rate measuring device comprising: the measurement flow path unit.

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