JP5527756B2 - Ultrasonic flow meter - Google Patents

Description

  The present invention relates to an ultrasonic flowmeter capable of measuring a gas flow rate or a flow velocity by transmitting and receiving ultrasonic waves between a pair of ultrasonic sensors.

  As a conventional ultrasonic flow meter, there is known a structure in which an ultrasonic sensor is attached to a pair of sensor holding portions branched obliquely forward and obliquely rearward from a measurement tube (see Patent Document 1).

JP 2009-85902 A (FIG. 1)

  However, in the above-described conventional ultrasonic flowmeter, the ultrasonic wave propagating through the tube wall of the measurement tube (hereinafter referred to as “housing noise”) has been a cause of reducing measurement accuracy.

  This invention is made | formed in view of the said situation, Comprising: It aims at provision of the ultrasonic flowmeter which can suppress housing noise.

In order to achieve the above object, an ultrasonic flowmeter according to the first aspect of the present invention has a pair of ultrasonic sensors attached to a pair of sensor holding portions branched obliquely forward and obliquely backward from a measurement tube. The measurement main body is covered with an outer sleeve from the side, and both ends of the enclosed space between the measurement tube and the outer sleeve are closed with a pair of annular lid walls, and the flow rate of gas flowing in the measurement tube Or in the ultrasonic flowmeter which can measure a flow velocity using an ultrasonic sensor, the measurement main-body part is the 1st main-body part structure containing one ultrasonic sensor, and the 2nd main body containing the other ultrasonic sensor. The first and second main body components are fixed to the outer sleeve, and the first and second main body components are held in a combined state, and the first and second main body components are fixed to the outer sleeve. Combined surface of the second main body component A gap for preventing the ultrasound transmission provided between, on the sensor holding portion, the branch pipe communicating with is provided in the measurement tube, coalescing surface, of one of the sensor holding portion of the measuring tube from one end thereof A pair of vertical line portions extending in parallel to the axial direction of the measuring tube to both sides of the sensor holding portion are connected to the tip ends of the pair of vertical line portions, and the branch pipe of one sensor holding portion is divided into two. It has the feature in the place which consists of a horizontal line part .

A second aspect of the present invention, the ultrasonic flowmeter according to claim 1, together with a pair of annular top wall is flared inwardly from both ends of the outer sleeve, the outer sleeve includes one annular cover wall The cover cap is detachably coupled to the end portion of the outer sleeve main body including the other annular lid wall, and the first main body component has a sensor holding portion in which the branch pipe is not divided into two parts, and both ends. The second body part structure has a sensor holding part in which the branch pipe is divided into two parts, and is attached to the outer surface of the second body part structure. The fixing projection piece provided and the inner projection wall provided in the outer sleeve main body are overlapped and screwed.

The invention according to claim 3, in the ultrasonic flowmeter according to claim 2, a plurality of mating surfaces of the two ends of the first body portion structure projects to extend a circumferential direction in the axial direction of the first body portion structure It is characterized in that it is provided with a fitting protrusion that is provided and abuts against the inner edge of the pair of annular lid walls.

The invention according to claim 4 is the ultrasonic flowmeter according to claim 2 or 3 , wherein the ultrasonic flowmeter protrudes outward from the outer surface of the second body portion constituting body and extends along the outer surface of the first body portion constituting body. A positioning recess that is provided with an outer surface adjacent wall that is opposed to the outer surface of the main body component structure, and that is recessed on either the outer surface or the outer surface adjacent wall of the first main body component structure; It has a feature in that it is provided with a positioning projection having a deformed cross section that enters the recess and partially contacts the inner surface of the positioning recess.

The invention according to claim 5 is the ultrasonic flowmeter according to any one of claims 2 to 4 , wherein the ultrasonic flowmeter has a cylindrical wall projecting from the outer surface of the outer sleeve body, and is defined on the inner side with respect to the enclosed space. It has a wiring processing space that has a wiring processing space partitioned by a wall and stores wiring connected to an electric circuit therein, and a part of the partition wall forms an inner surface protruding wall, and a plurality of inner surface protruding walls The fixing projection piece holds a plurality of terminal fittings in a penetrating state, and an electric wire extending from a pair of ultrasonic sensors is connected to one end of each of the terminal fittings. It is characterized in that the other end of the metal fitting is connected to the electric circuit through the terminal insertion hole.

According to a sixth aspect of the present invention, in the ultrasonic flowmeter according to any one of the first to fifth aspects, the liquid that has entered the branch pipe is surrounded between the inner surface of the branch pipe and the ultrasonic sensor. It is characterized in that an internal communication passage that can be discharged into the space is provided.

According to a seventh aspect of the present invention, in the ultrasonic flowmeter according to the sixth aspect , the liquid that has entered the enclosed space can be discharged to the outside between the both end portions of the measurement tube and the inner edge portions of the pair of annular lid walls. It is characterized in that an external communication path is provided.

[Effect of claim 1]
According to invention of Claim 1, a measurement main-body part is divided | segmented into the 1st main-body part structure body containing one ultrasonic sensor, and the 2nd main-body part structure body containing the other ultrasonic sensor, These Since the ultrasonic transmission preventing gap is provided between the combined surfaces of the first and second main body constituting bodies, it is possible to suppress or eliminate the casing noise propagating through the tube wall of the measurement tube. As a result, it is possible to prevent a decrease in measurement accuracy caused by housing noise.

In addition, according to the present invention, it is possible to suppress the influence of the gap for preventing ultrasonic transmission on the flow of gas in the measurement tube and perform measurement stably.

[Invention of claim 2 ]
According to the second aspect of the present invention, the first body part structure can be fixed to the outer sleeve by fitting both end parts to the inner edge part of the pair of annular lid walls. The outer sleeve can be fixed to the outer sleeve by screwing it on the inner surface protruding wall provided on the outer sleeve body.

[Invention of claim 3 ]
According to the invention of claim 3 , since both end portions of the first body portion constituting body and the inner edge portions of the pair of annular lid walls can be brought into partial contact, the first body constituting body and the outer sleeve Propagation of housing noise between the two can be suppressed. That is, the propagation of the housing noise between the pair of ultrasonic sensors via the outer sleeve can be suppressed.

[Invention of claim 4 ]
According to the invention of claim 4 , when the second body portion constituting body is fixed to the outer sleeve body, the first body portion constituting body is rotated around the outer sleeve body by the uneven engagement between the positioning protrusion and the positioning recessed portion. Stopping and retaining can be achieved. Moreover, since the positioning protrusion is configured to partially abut on the inner surface of the positioning recess, the propagation of the housing noise between the first body part structure and the second body part structure is suppressed. can do.

[Invention of claim 5 ]
According to the invention of claim 5 , the transmission / reception signal of the ultrasonic sensor is inputted / outputted to / from the electric circuit through the terminal fitting penetrating the partition wall. Further, by holding the plurality of terminal fittings in the penetrating state on the fixing protrusion, the fixing protrusion for fixing the second main body constituting body to the outer sleeve main body can also be used as a terminal block.

[Invention of claim 6 ]
According to the sixth aspect of the present invention, it is possible to prevent a situation in which liquid is accumulated in the branch pipe, and an operation of extracting the liquid stored in the branch pipe becomes unnecessary.

[Invention of Claim 7 ]
According to the seventh aspect of the present invention, it is possible to prevent a situation where liquid is stored in the surrounding space, and an operation for extracting the liquid stored in the surrounding space is not required.

Plan sectional view of the ultrasonic flowmeter according to the present embodiment Side view of ultrasonic flowmeter Disassembled perspective view of ultrasonic flowmeter HH line sectional view in FIG. FF sectional view taken on the line in FIG. DD line sectional view in FIG. EE sectional view in FIG. Enlarged sectional view of the sensor holder Disassembled perspective view of the measurement body Enlarged view of the portion surrounded by the broken-line circle in FIG. (A) Side view, (B) Top view of the measurement main unit (A) Cross section of positioning protrusion, (B) Cross section of modification of positioning protrusion, (C) Cross section of modification of positioning protrusion Top view of the ultrasonic flowmeter connected to the gas supply pipe

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the ultrasonic flowmeter 10 of the present embodiment covers the measurement main body 30 from the side with the outer sleeve 11, and both ends of the enclosed space 70 between the measurement tube 31 and the outer sleeve 11. Is closed by a pair of annular lid walls 13, 13 provided on the outer sleeve 11, and the measurement pipe 31 is configured to measure the gas (air, propane gas, city) via the annular lid walls 13, 13. Gas, butane air, hydrogen, etc.) can be connected in the middle of a gas feed pipe 90 (see FIG. 13).

  The measurement main body 30 includes a pair of sensor holding portions 32, 32 that are branched obliquely forward and diagonally at both ends of the measurement tube 31. The ultrasonic sensors 50, 50 are provided to the sensor holding portions 32, 32, respectively. Hold it. Then, ultrasonic waves are transmitted and received between the pair of ultrasonic sensors 50, 50, that is, in a direction obliquely intersecting with the axial direction of the measuring tube 31, and the ultrasonic waves in the forward direction along the gas flow are detected. Based on the difference between the propagation time of the sound wave and the propagation time of the ultrasonic wave in the opposite direction against the gas flow, the flow velocity and flow rate of the gas passing through the measurement tube 31 can be measured.

  The measuring tube 31 has a cylindrical shape. In the measuring tube 31, the inner diameter of the intermediate portion in the axial direction is constant, whereas the inner diameter of both end portions in the axial direction is slightly increased toward the end (see FIG. 2). That is, the cross-sectional area of the flow path through which the gas passes is gradually narrowed from both end portions in the axial direction toward the intermediate portion.

  The sensor holding portions 32, 32 include branch pipes 33, 33 that project obliquely from the outer peripheral surface of the measurement pipe 31, and sensor holding holes 34, 34 are formed inside the branch pipes 33, 33. The sensor holding holes 34, 34 communicate the measuring tube 31 inside and outside. The ultrasonic sensors 50, 50 are inserted and assembled into the sensor holding holes 34, 34 from the distal end openings of the branch pipes 33, 33. Here, as shown in FIG. 1, the branch pipes 33, 33 are not in contact with the inner peripheral surface of the outer sleeve 11. Specifically, a gap of 0.5 mm or more is provided between the inner peripheral surface of the outer sleeve 11.

  Each sensor holding portion 32, 32 is provided with a plurality of positioning protrusions 34A that protrude in a stepped manner from the inner surface of the sensor holding hole 34 and extend along the axial direction of the branch pipe 33 (see FIG. 6). . In addition, a plurality of positioning protrusions 34 </ b> B protruding toward the inner side of the sensor holding hole 34 are provided at the opening edge of the branch pipe 33 (see FIG. 5). Each positioning protrusion 34B is formed on an extension line of the positioning protrusion 34A.

  The ultrasonic sensor 50 has a flat cylindrical shape, and is provided with a substantially dome-shaped transmission / reception surface 51 on the front surface. Further, as shown in FIG. 9, a lead wire 52 extends from the rear surface opposite to the wave transmitting / receiving surface 51, and an annular protrusion 53 protruding in a stepped shape is provided on the outer peripheral surface.

  As shown in FIG. 1, the ultrasonic sensor 50 is assembled in the sensor holding hole 34 via, for example, a rubber vibration isolating member 55. The vibration isolation member 55 has a cylindrical structure, and the ultrasonic sensor 50 is press-fitted inside the vibration isolation member 55. The vibration isolation member 55 surrounds the outer peripheral surface (annular protrusion 53) of the ultrasonic sensor 50, and the wave transmitting / receiving surface 51 and the rear surface are exposed from the vibration isolation member 55.

  A flange wall 55A projects from the rear end of the vibration isolating member 55 toward the side (see FIG. 9). When the ultrasonic sensor 50 is press-fitted into the vibration isolating member 55 and inserted into the sensor holding hole 34 through the distal end opening of the branch pipe 33, the flange wall 55A protrudes into the end faces of the positioning protrusions 34A and 34A provided in the sensor holding hole 34. When applied (see FIGS. 6 and 8), the ultrasonic sensor 50 is positioned in the axial direction of the branch pipe 33.

  In addition, the positioning projections 34B and 34B provided at the distal end opening edge of the branch pipe 33 are abutted against the outer surface of the collar wall 55A in a state where the collar wall 55A abuts against the end surface of the positioning protrusion 34A. The sensor 50 is positioned in the radial direction (see FIG. 5). As shown in FIG. 4, plate-like pressing members 56, 56 are screwed to the distal end portion of the branch pipe 33, and a flange wall 55A is sandwiched between the pressing members 56, 56 and the end surface of the positioning protrusion 34A. (See FIG. 8). In this way, the ultrasonic sensor 50 is positioned and fixed to the sensor holding part 32.

  Here, by providing the positioning protrusion 34A and the positioning protrusion 34B protruding inside the sensor holding hole 34, as shown in FIG. 1 between the vibration isolating member 55 and the inner surface of the sensor holding hole 34. An internal communication path 57 that communicates between the internal space (sensor holding hole 34) of the branch pipe 33 and the surrounding space 70 is formed. The internal communication path 57 is capable of passing a liquid (for example, a liquid component contained in the gas or a gas obtained by liquefying the gas), and has a width of 0.5 mm or more, for example. Thereby, it is possible to prevent the liquid from being stored in the sensor holding hole 34, and the ultrasonic sensor 50 and the sensor holding unit 32 are communicated by the liquid without passing through the vibration isolating member 55. It is possible to prevent a situation in which vibration propagates to the measurement tube 31 through the liquid. In addition, it is possible to prevent the transmission / reception wave surface 51 from being immersed in the liquid.

  As shown in FIG. 1, the ultrasonic sensor 50 and the vibration isolation member 55 are also not in contact with the inner surface of the outer sleeve 11. Specifically, a gap of 0.5 mm or more is provided between the inner surface of the outer sleeve 11.

  As shown in FIG. 1, the pair of annular lid walls 13, 13 protrudes inward from both end portions of the outer sleeve 11, and through the communication holes 14, 14 penetrating through the center portions of both annular lid walls 13, 13, The measurement pipe 31 and the gas supply pipe 90 (see FIG. 13) can communicate with each other. An opening edge on the outer surface side of the annular lid wall 13 in the communication hole 14 is chamfered in a tapered shape.

  On the other hand, spigot portions 14 </ b> A and 14 </ b> A are formed at the opening edge on the inner surface side of the annular lid wall 13 in the communication hole 14. Correspondingly, the spigot portions 31A and 31A are also formed at both ends of the measuring tube 31 (see FIG. 9), and the spigot portions 14A and 31A are concavo-convexly fitted.

  As shown in FIG. 9, a plurality of fitting protrusions 35 extending in the axial direction of the measuring tube 31 protrude from the outer peripheral surface of the inlay portion 31 </ b> A of the measuring tube 31. Each fitting projecting ridge 35 has a shape obtained by vertically dividing a cylindrical body (a so-called “ridge shape”), and abuts against the inner peripheral surface of the spigot portion 14 </ b> A of the annular lid wall 13. Thereby, both end portions of the measuring tube 31 are positioned in the radial direction with respect to the outer sleeve 11. Further, the outer surface of the spigot part 31A and the inner side surface of the spigot part 14A are partially in contact with each other by the plurality of fitting protrusions 35.

  As shown in FIG. 9, a plurality of notches 36 are formed in the inlay portion 31 </ b> A of the measurement tube 31. These notches 36 are provided, for example, at intermediate positions between the fitting protrusions 35 and 35 adjacent to each other in the circumferential direction. As shown in an enlarged view in FIG. 10, an external communication path 58 that communicates between the enclosed space 70 and the communication hole 14 is formed by each notch 36. The external communication path 58 can pass liquid, and has a width of 0.5 mm or more, for example. Thereby, the liquid that has entered the enclosed space 70 can be discharged to the outside of the ultrasonic flowmeter 10.

  Specifically, for example, when the ultrasonic flowmeter 10 is attached so that the axial direction of the measurement tube 31 is horizontal, the liquid in the enclosed space 70 is externally communicated by the gas passing through the measurement tube 31. It is possible to suck out from the path 58. When the ultrasonic flowmeter 10 is attached so that the axial direction of the measurement tube 31 is vertical, the liquid in the enclosed space 70 is discharged by its own weight from the external communication path 58 located on the lower side. .

  As shown in FIG. 3, the outer sleeve 11 includes a cover cap 22 including one annular lid wall 13 and one end portion of the outer sleeve main body 17 including the other annular lid wall 13 (a downstream end portion in the present embodiment). Hereinafter, it is detachably coupled to the “coupled end”. And the measurement main-body part 30 mentioned above is inserted and assembled | attached from the insertion port 18 open | released at the coupling end of the outer sleeve main body 17. FIG.

  The cover cap 22 includes a cap cylinder 23 that stands up at a right angle from the outer peripheral edge of the annular lid wall 13, and the cap cylinder 23 is fitted and fixed to the outside of the coupling end of the outer sleeve body 17.

  Specifically, an O-ring groove 19 and an annular locking groove 21 are formed in a recessed manner on the outer peripheral surface of the coupling end of the outer sleeve body 17. As shown in FIG. 1, the O-ring groove 19 is formed on the end side from the annular locking groove 21 and is deeper than the annular locking groove 21. The O-ring 20 fitted in the O-ring groove 19 is crushed and adhered to the inner peripheral surface of the cap cylinder 23. Thereby, the space between the outer sleeve main body 17 and the cover cap 22 is sealed in an airtight state.

  Further, screw holes 22A are formed through a plurality of positions in the circumferential direction of the cap cylinder 23 (only one screw hole 22A is shown in FIG. 1), and set screws 24 ( The tip of FIG. 3) is abutted against the outer surface of the annular locking groove 21. As a result, the cover cap 22 is prevented from rotating and coming off from the outer sleeve body 17.

  A display connection portion 15 that is open to the side is formed in an intermediate portion in the axial direction of the outer sleeve 11 (outer sleeve main body 17). As shown in FIG. 2, the display connection portion 15 has, for example, a cylindrical shape whose diameter increases stepwise toward the side, and stands from the outer peripheral surface of the outer sleeve 11. A display unit 93 is detachably attached to the opening end of the display connection unit 15. The display unit 93 calculates the flow rate based on the propagation time of the ultrasonic wave between the ultrasonic sensors 50 and 50 and displays the result.

  The display connection portion 15 corresponds to a “wiring storage portion” of the present invention, and various components are accommodated in a wiring processing space 15A formed inside thereof. For example, a pressure sensor (not shown) for measuring the gas pressure and a harness 94 are accommodated. The harness 94 corresponds to “wiring” of the present invention, and is connected to an airtight terminal 49 described later. The harness 94 and the airtight terminal 49 relay between the ultrasonic sensors 50 and 50 and an electric circuit 97 provided in the display unit 93 for calculating the flow velocity and the flow rate.

  The wiring processing space 15 </ b> A is partitioned from the surrounding space 70 by the partition wall 16. The partition wall 16 has a container structure that bulges from the inner peripheral surface of the outer sleeve 11 toward the measurement tube 31 (enclosed space 70), and a part of the partition wall 16 forms an inner surface protruding wall 16 </ b> A perpendicular to the axial direction of the outer sleeve 11. It has become.

  As shown in FIG. 2, the measurement main body 30 (more precisely, a second main body portion constituting body 62 described later) is fixed to the inner surface protruding wall 16 </ b> A of the partition wall 16 in the axial direction of the outer sleeve main body 17. A projecting piece 42 is provided. The fixing protrusion 42 is positioned at a position 90 degrees away from the pair of sensor holding portions 32 and 32 in the circumferential direction of the measurement tube 31 and one sensor holding portion 32 (in detail in the axial direction of the measurement tube 31). Are provided unevenly at positions close to the downstream sensor holding part 32). As shown in FIG. 4, the fixing protrusion 42 has an arcuate plate shape that protrudes to the side of the measurement tube 31 and extends in the circumferential direction of the measurement tube 31.

  As shown in FIG. 9, screw holes 48 are formed at positions near both ends in the longitudinal direction of the fixing projection piece 42. The fixing projecting piece 42 is overlapped with the inner surface protruding wall 16A in the insertion direction of the measurement main body 30 with respect to the outer sleeve body 17, and the inner surface protruding wall 16A is formed by screws 96, 96 (see FIG. 4) penetrating the screw holes 48, 48. It is screwed to. Note that the outer surface of the fixing protrusion 42 curved in an arc is not in contact with the inner peripheral surface of the outer sleeve body 17.

  As shown in FIG. 4, a plurality (specifically, four) of terminal holding cylinders 43 are provided between the screw holes 48 of the fixing protrusion 42. The terminal holding cylinder 43 protrudes from the fixing protrusion 42 to the side opposite to the inner surface protruding wall 16 </ b> A and extends in parallel with the axial direction of the measuring tube 31. Further, the terminal holding cylinders 43 are arranged in a straight line between the two screw holes 48.

  An airtight terminal 49 in which a plurality of (for example, four) terminal fittings 45 and a rubber airtight member 46 are integrated is attached to the surface of the fixing protrusion 42 opposite to the terminal holding cylinder 43. ing. The airtight terminal 49 is formed by inserting a needle-shaped terminal fitting 45 into the airtight member 46.

  As shown in FIG. 2, each terminal fitting 45 of the airtight terminal 49 is inserted through the terminal holding cylinder 43. A base end portion of the terminal fitting 45 that protrudes from the tip end of the terminal holding cylinder 43 is connected to lead wires 52 and 52 extending from the ultrasonic sensors 50 and 50 in the enclosed space 70. Further, the tip of each terminal fitting 45 protrudes into the wiring processing space 15A from a plurality (four) of terminal insertion holes 16B formed through the inner surface protruding wall 16A, and is connected to the electric circuit 97 via the harness 94. It is connected. Here, the space between each terminal fitting 45 and the terminal insertion hole 16B is blocked by the airtight member 46 so that the gas in the enclosed space 70 does not enter the wiring processing space 15A.

  By the way, as shown in FIG. 9, the measurement main body 30 of the ultrasonic flowmeter 10 includes a first main body constituting body 61 including an upstream ultrasonic sensor 50 (the left ultrasonic sensor 50 in FIG. 2). And a second main body constituting body 62 including the downstream ultrasonic sensor 50 (right ultrasonic sensor 50 in FIG. 2). And these 1st and 2nd main-body-part structure bodies 61 and 62 are each fixed to the outer sleeve 11, and the 1st and 2nd main-body-part structure bodies 61 and 62 are hold | maintained in a united state, and outer A measurement main body 30 is formed in the sleeve 11.

  Here, the combined surface of the first body part constituting body 61 and the second body part constituting body 62 is as follows. That is, as shown in FIG. 11, the measurement tube 31 extends in parallel to the axial direction of the measurement tube 31 from the downstream end of the sensor holding portion 32 to both sides of the downstream sensor holding portion 32. The pair of vertical line portions L1 and L1 and a horizontal line portion L2 that communicates between the ends of the pair of vertical line portions L1 and L1 and divides the downstream branch pipe 33 into two.

  As shown in FIG. 9, the first main body constituting body 61 has an upstream sensor holding portion 32 that is not divided into two parts and most of the measuring tube 31, and both end portions are 1 as described above. The outer sleeve 11 is positioned by being fitted to the inner edge portions (inlay portions 31A, 31A) of the pair of annular lid walls 13, 13.

  On the other hand, the second main body constituting body 62 includes the downstream sensor holding portion 32 and the fixing protrusions 42 in which the branch pipe 33 is divided into two, and each terminal fitting of the airtight terminal 49 as described above. In a state where 45 is inserted into the terminal insertion hole 16B, the fixing projecting piece 42 is screwed to the inner surface protruding wall 16A to be positioned and fixed to the outer sleeve 11.

  As shown in FIG. 9, the second main body unit structure 62 has an outer surface adjacent wall 44 that is curved and extends along the outer surface of the first main body unit 61 (the outer peripheral surface of the measurement tube 31). ing. The outer surface adjacent wall 44 extends in parallel with the axial direction of the measuring tube 31 from the inner edge of the fixing protrusion 42 and protrudes away from the inner surface protruding wall 16A (see FIG. 2). Further, in a state where the first and second main body constituent members 61 and 62 are fixed to the outer sleeve 11, the inner surface of the outer surface adjacent wall 44 and the outer surface of the first main body constituent member 61 (the outer peripheral surface of the measuring tube 31). There is a gap between them.

  Further, as shown in FIG. 2, a positioning protrusion 62 </ b> A protrudes from the inner surface of the outer surface adjacent wall 44. Corresponding to the positioning protrusion 62A, a positioning recess 61A is formed in a recessed manner on the outer surface of the first main body constituting body 61, and the positioning protrusion 62A is unevenly fitted to the positioning recess 61A. When the second main body constituting body 62 is fixed to the outer sleeve 17 main body, the first main body constituting body 61 can be made non-rotatable with respect to the outer sleeve main body 17 and can be removed from the outer sleeve main body 17. Can be stopped. That is, the first main body component 61 is positioned in the axial direction and the rotational direction.

  A gap G1 for preventing ultrasonic transmission is provided between the combined surfaces of the first main body component 61 and the second main body component 62 fixed as described above (FIG. 11). reference). The width of the gap G1 is such that, for example, the first main body component 61 and the second main body component 62 are not communicated by the liquid contained in the measurement target gas flowing in the measurement tube 31. It has a size (specifically, 0.5 mm or more). Note that the width of the gap G1 may be appropriately set according to the type of gas to be measured, the temperature, the viscosity of the liquid that can be contained in the gas, and the like.

  Here, the positioning protrusion 62A has a cross-shaped cross section as shown in FIG. 12A, and is in partial contact with four locations on the inner peripheral surface of the positioning recess 61A. As shown in FIG. 2, the tip of the positioning protrusion 62A is not in contact with the bottom of the positioning recess 61A. That is, the first body part constituting body 61 and the second body part constituting body 62 are arranged in a separated state from each other at a portion other than the contact portion between the positioning protrusion 62A and the positioning recess 61A.

  Note that the cross-sectional shape of the positioning protrusion 62A is not limited to a cross-shaped cross section as long as it has a different shape that partially contacts the inner surface of the positioning recess 61A. For example, as shown in FIG. 12B, a triangle inscribed in the positioning recess 61A may be used, or as shown in FIG. 12C, a rectangle inscribed in the positioning recess 61A may be used.

  The configuration of the ultrasonic flowmeter 10 of the present embodiment is as described above. The ultrasonic flow meter 10 is assembled, for example, according to the following procedure.

  First, the pair of ultrasonic sensors 50 and 50 are press-fitted into the vibration isolating members 55 and 55, respectively, and assembled to the sensor holding portions 32 and 32. Specifically, the ultrasonic sensor 50 is inserted from the distal end opening of the branch pipe 33, and the flange wall 55 </ b> A of the vibration isolation member 55 is abutted against the positioning protrusion 34 </ b> A in the sensor holding hole 34. Next, the pressing members 56 and 56 are overlapped with the vibration isolating member 55 and screwed to the tip of the branch pipe 33. This operation is performed for each of the sensor holding portions 32 and 32 of the first main body unit structure 61 and the second main body unit structure 62, respectively.

  Next, the airtight terminal 49 is attached to the fixing projection piece 42 of the second main body component 62. That is, the four terminal fittings 45 provided in the airtight terminal 49 are inserted into the corresponding terminal holding cylinders 43 respectively. Next, the positioning projections 62A of the second main body part 62 are fitted into the positioning recesses 61A of the first main body part 61, and the first and second main body parts 61 and 62 are fitted. Combine. Next, the lead wires 52 and 52 of the ultrasonic sensors 50 and 50 are connected (soldered) to the base end portion of the terminal fitting 45 penetrating the fixing protrusion 42.

  Next, the measurement main body 30 in which the first and second main body constituent bodies 61 and 62 are combined is inserted from the insertion port 18 of the outer sleeve main body 17, and the upstream end of the first main body constituent body 61 is inserted. The inlay portion 31 </ b> A formed in the portion is fitted into the inlay portion 14 </ b> A formed in the annular lid wall 13 of the outer sleeve main body 17. Here, in the process of inserting the measurement main body 30 into the outer sleeve main body 17, each terminal fitting 45 held by the fixing protrusion 42 is inserted into the corresponding terminal insertion hole 16 </ b> B of the inner surface protruding wall 16 </ b> A. The tip of the metal fitting 45 enters the wiring processing space 15A. When the inlay portions 14A and 31A are fitted to each other, the fixing protruding piece 42 and the inner surface protruding wall 16A are brought into surface contact, and the airtight member 46 is press-fitted into the terminal insertion hole 16B. The space between the terminal fitting 45 is sealed.

  Next, screws 96 and 96 are inserted from the insertion port 18, passed through the screw holes 48 and 48 of the fixing protrusion 42, and screwed into a spiral hole (not shown) of the inner surface protruding wall 16 </ b> A. As a result, the second main body component 62 is fixed to the outer sleeve 11. Further, since the second body part constituting body 62 is fixed, the first body part constituting body 61 is prevented from rotating and coming off with respect to the outer sleeve body 17.

  Next, the cover cap 22 is fitted to the coupling end of the outer sleeve main body 17 to close the insertion port 18, and the cover cap 22 and the outer sleeve main body 17 are fixed so as not to be detached by the set screw 24. At this time, the inlay portion 31 </ b> A formed at the downstream end portion of the first body portion constituting body 61 and the inlay portion 14 </ b> A formed in the annular lid wall 13 of the cover cap 22 are concavo-convexly fitted. As a result, both end portions of the first main body component 61 are positioned by the outer sleeve 11 in the axial direction and the radial direction. When the cover cap 22 is attached, the O-ring 20 is compressed and deformed, and the space between the outer sleeve body 17 and the cover cap 22 is sealed.

  Subsequently, the harness 94 and each terminal fitting 45 are connected in the wiring processing space 15A, the display unit 93 is attached to the display connection unit 15, and the electric circuit 97 in the display unit 93 and the harness 94 are connected. . The ultrasonic flow meter 10 is now complete.

  The ultrasonic flow meter 10 is attached to the gas supply pipe 90 as follows. That is, as shown in FIG. 13, both the annular lid walls 13 and 13 of the outer sleeve 11 are abutted against both flanges 90F and 90F surfaces of the gas supply pipe 90 through the packings 91 and 91, and in this state both The flanges 90F and 90F are fastened with a plurality of bolts 98 (specifically, stud bolts of all screws). Thereby, the ultrasonic flowmeter 10 is fixed in the middle of the gas supply pipe 90, and the gas flowing through the gas supply pipe 90 passes through the measurement tube 31.

  When measurement is performed by the ultrasonic flow meter 10, the ultrasonic wave transmitted from one ultrasonic sensor 50 is received by the other ultrasonic sensor 50 across the gas flowing in the measurement tube 31. . Based on the propagation time of the ultrasonic wave between the pair of ultrasonic sensors 50 and 50, the flow velocity and flow rate of the gas passing through the measurement tube 31 are measured. Here, when the ultrasonic sensor 50 transmits ultrasonic waves, vibration that cannot be completely absorbed by the vibration isolating member 55 can leak into the sensor holding portion 32 and become housing noise.

  In contrast, in the ultrasonic flowmeter 10 of the present embodiment, the measurement main body 30 includes a first main body component 61 that holds one ultrasonic sensor 50 and a first ultrasonic sensor 50 that holds the other ultrasonic sensor 50. It is divided into two main body part constituting bodies 62. Then, by fixing the first and second body part constituting bodies 61 and 62 to the outer sleeve 11, respectively, the first and second body part constituting bodies 61 and 62 are held in a combined state, and the first A gap G1 for preventing ultrasonic transmission is provided between the first and second main body components 61 and 62. The housing noise does not propagate across this gap G1. Further, the positioning protrusion 62A in which the first main body component 61 and the second main body component 62 are in contact with each other partially abuts on a part of the inner surface of the positioning recess 61A. With these, it is possible to suppress or eliminate the housing noise propagating through the measurement tube 31.

  In addition, the outer surfaces of the spigot portions 31A and 31A provided in the first main body constituting body 61 are partially in contact with part of the inner side surfaces of the spigot portions 14A and 14A of the annular flange walls 13 and 13. . Therefore, the propagation of the housing noise between the first main body unit 61 and the outer sleeve 11 can be suppressed.

  Therefore, according to the ultrasonic flowmeter 10 of the present embodiment, it is possible to prevent a decrease in measurement accuracy due to housing noise.

  Further, the combined surface of the first body part constituting body 61 and the second body part constituting body 62 extends from the end of one sensor holding part 32 of the measurement tube 31 to both side parts of the one sensor holding part 32. The pair of vertical line portions L1 and L1 extending in parallel with the axial direction of the measuring tube 31 communicates with the tips of the pair of vertical line portions L1 and L1, and two branch pipes 33 of one sensor holding unit 32 are connected. By including the horizontal line portion L2 to be divided, the influence of the gap G1 on the gas flow in the measurement tube 31 can be suppressed, and the measurement can be performed stably.

  Further, the liquid that has entered the branch pipes 33 and 33 (sensor holding holes 34 and 34) of the sensor holding portions 32 and 32 is discharged from the internal communication path 57 to the enclosure space 70, and the liquid that has entered the enclosure space 70 is externally discharged. It can be discharged from the communication path 58 to the outside of the ultrasonic flowmeter 10. Thereby, the operation | work which extracts the liquid stored in the branch pipes 33 and 33 and the enclosed space 70 becomes unnecessary, and a maintainability improves.

  In addition, the fixing protrusions 42 that fix the second main body constituting body 62 to the outer sleeve 11 are held in a penetrating state so that the fixing protrusions 42 can be used as terminal blocks. it can.

  Furthermore, the width of the gap G1 is set to a size that prevents the liquid between the first body part constituting body 61 and the second body part constituting body 62 from being communicated (continuously) with the liquid. Even when the gas contains a liquid, it is possible to prevent the housing noise from propagating.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various modifications are possible within the scope of the invention other than the following. It can be changed and implemented.
(1) In the above embodiment, the second main body constituting body 62 is disposed on the downstream side, but may be disposed on the upstream side.

  (2) In the above embodiment, the first main body component 61 is prevented from rotating with respect to the outer sleeve 11 by the concave-convex engagement between the positioning protrusion 62A and the positioning concave 61A. An uneven engagement portion that positions (stops) the first body portion constituting body 61 in the circumferential direction may be provided between one end portion of the body 61 and the annular lid wall 13 provided in the outer sleeve body 17. . As a result, the first main body part structure 61 and the second main body part structure 62 can be combined in a completely non-contact state, and propagation of housing noise can be prevented more reliably. become.

  (3) In the above embodiment, the measurement main body 30 is divided into two, but it may be divided into three or more.

( 4 ) In the above embodiment, the positioning projection 62A is provided on the second main body constituting body 62 and the positioning recess 61A is provided on the first main body constituting body 61, but the first main body constituting body 61 is provided. A positioning protrusion may be provided on the second body portion constituting body 62 and a positioning recess may be provided.

( 5 ) In the above embodiment, the plurality of fitting protrusions 35 are provided on the outer peripheral surface of both end portions (inlay portions 31A, 31A) of the measuring tube 31, but the inner edge portions of the annular member walls 13, 13 ( A plurality of fitting protrusions may be provided on the inner surface of the inlay portions 14A and 14A.

( 6 ) In the above embodiment, the present invention is applied to the ultrasonic flowmeter 10 in which the pair of ultrasonic sensors 50, 50 are arranged to face each other in a direction obliquely intersecting the axial direction of the measurement tube 31. The present invention may be applied to an ultrasonic flowmeter in which ultrasonic waves are reflected on the inner surface of the measurement tube 31 to transmit and receive waves.

11 outer sleeve 13 annular lid wall 15 display connection part (wiring storage part)
15A Wiring processing space 16 Partition wall 16A Inner surface protruding wall 16B Terminal insertion hole 17 Outer sleeve main body 22 Cover cap 30 Measurement main body part 31 Measuring pipe 32 Sensor holding part 33 Branch pipe 34 Sensor holding hole 34A Positioning protrusion 34B Positioning protrusion 35 Fitting Projecting ridge 36 Notch 42 Fixing piece 44 Outer surface adjacent wall 45 Terminal fitting 50 Ultrasonic sensor 57 Internal communication path 58 External communication path 61 First body part structure body 62 Second body part structure body 61A Positioning Recess 62A Positioning projection 70 Surrounding space 94 Harness (wiring)
97 Electric circuit G1 Gap for preventing ultrasonic transmission L1 Vertical line L2 Horizontal line

Claims (7)

A measurement main body portion formed by attaching a pair of ultrasonic sensors to a pair of sensor holding portions branched obliquely forward and obliquely rearward from the measurement tube is covered with an outer sleeve from the side, and the measurement tube and the outer sleeve In the ultrasonic flow meter that can measure the flow rate or flow velocity of the gas flowing in the measurement tube using the ultrasonic sensor, with the structure in which both ends of the enclosed space between the two are closed with a pair of annular lid walls,
The measurement main body is divided into a first main body constituting body including one of the ultrasonic sensors and a second main body constituting body including the other ultrasonic sensor,
The first and second main body parts are fixed to the outer sleeve to hold the first and second main body parts in a combined state, and the first and second main body parts. A gap for preventing ultrasonic transmission is provided between the combined surfaces of the components ,
The sensor holding unit includes a branch pipe communicating with the measurement pipe,
The united surface has a pair of vertical line portions extending in parallel with the axial direction of the measuring tube from one end of the measuring tube to the side of the one sensor holding unit, An ultrasonic flowmeter comprising a horizontal line portion that communicates between the ends of the pair of vertical line portions and divides the branch pipe of the one sensor holding portion into two . The pair of annular lid walls project inward from both ends of the outer sleeve, and the outer sleeve includes a cover cap including one annular lid wall and an outer sleeve body including the other annular lid wall. Removably coupled to the end of the
While the first body portion constituting body has the sensor holding portion in which the branch pipe is not divided into two and both end portions are fitted and fixed to inner edge portions of the pair of annular lid walls,
The second main body component has the sensor holding part in which the branch pipe is divided into two parts,
2. The ultrasonic flowmeter according to claim 1 , wherein a fixing projecting piece provided on an outer surface of the second main body constituting body and an inner surface projecting wall provided on the outer sleeve main body are overlapped and screwed together. . A fitting that protrudes from the fitting surfaces at both ends of the first main body constituting body, extends in the axial direction of the first main body constituting body, and is provided in a plurality in the circumferential direction, and abuts against inner edges of the pair of annular lid walls The ultrasonic flowmeter according to claim 2, further comprising a joint protrusion . Projecting outward from the outer surface of the second main body component, extending along the outer surface of the first main body component, and facing the outer surface opposite to the outer surface of the first main body component Walls are provided,
A positioning recess recessed in one of the outer surface of the first main body component and the adjacent wall of the outer surface, and a positioning with a deformed cross section that protrudes into the positioning recess and partially contacts the inner surface of the positioning recess. The ultrasonic flowmeter according to claim 2, further comprising a protrusion . Wiring having a cylindrical wall projecting from the outer surface of the outer sleeve main body and having a wiring processing space partitioned by a partition wall on the inner side with a partition wall and storing wiring connected to an electric circuit therein With storage,
A part of the partition wall constitutes the inner surface protruding wall, and a plurality of terminal insertion holes are formed through the inner surface protruding wall,
The fixing protrusion holds a plurality of terminal fittings in a penetrating state, and an electric wire extending from the pair of ultrasonic sensors is connected to one end of the terminal fitting, while the other end of the terminal fitting is The ultrasonic flowmeter according to claim 2, wherein the ultrasonic flowmeter is connected to the electric circuit through the terminal insertion hole . Wherein the inner surface of the branch pipe between the ultrasonic sensor, any claim 1 to 5, characterized in that the liquid that has entered into the branch pipe internal communication path capable of discharging into the enclosed space provided The ultrasonic flowmeter according to claim 1. Claim wherein between the inner edge of both end portions and said pair of annular lid wall of the measuring tube, characterized in that the liquid that has entered the enclosed space external communication passage capable of discharging to the outside is provided 6. The ultrasonic flowmeter according to 6 .

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