JP2006337059A - Ultrasonic flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter which can reduce product-to-product variations in performance. <P>SOLUTION: A pair of ultrasonic sensors 32, 32 are held by a sensor-holding piece 37 integrally-molded with a measuring tube 31 (a plurality of measuring tube structures 40, 40), thereby reducing the variations in the distance between the ultrasonic sensors 32, 32 and the measuring tube 31 and the distance between the ultrasonic sensors 32, 32 as compared to conventional types, and hence reducing the product-to-product variations in performance (more specifically, measurement precision) in the ultrasonic flowmeter 10 as compared to conventional ones. Since the measuring tube 31 is configured by the two measuring tube structures 40, 40 which are vertically divided parallel to its axial direction, flexibility in the shape of an internal area (a flow channel 31a) of the measuring tube 31 are enhanced, by allowing, for example, a constriction part 35 to be formed at the opening edge of the measuring tube 31. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a meter case, a measurement tube that is accommodated in the meter case and in which a fluid flows, and is spaced apart from the openings at both ends of the measurement tube, and each other across the inner region of the measurement tube The present invention relates to an ultrasonic flowmeter that includes a pair of opposed ultrasonic transducers and measures a flow rate based on a propagation time of ultrasonic waves transmitted and received between the pair of ultrasonic transducers.

  The conventional ultrasonic flowmeter has a structure in which a measuring tube and a pair of ultrasonic transducers are separately assembled to a holder provided inside a meter case.

  However, in the conventional ultrasonic flowmeter described above, the assembly error of the measurement tube to the holder and the assembly error of the ultrasonic transducer to the holder can occur. There was a problem in that the distance between the acoustic transducers varied and the performance between individual products varied.

  In addition, prior art documents related to the present invention could not be found.

  This invention is made | formed in view of the said situation, and aims at provision of the ultrasonic flowmeter which can suppress the dispersion | variation in the performance between products.

  In order to achieve the above object, an ultrasonic flowmeter according to the invention of claim 1 includes a meter case, a measurement tube that is accommodated in the meter case and in which a fluid flows, and ends of both ends of the measurement tube. And a pair of ultrasonic transducers arranged apart from the opening and facing each other across the inner region of the measurement tube, and ultrasonic waves transmitted and received between the pair of ultrasonic transducers In an ultrasonic flowmeter that measures the flow rate based on the propagation time, a measurement tube is configured by assembling a plurality of measurement tube components obtained by vertically dividing the measurement tube, and at least one of these measurement tube components The ultrasonic transmitter / receiver is characterized in that a transmitter / receiver holding part for holding the ultrasonic transmitter / receiver at a position separated from the opening of the measuring tube is provided integrally.

  According to a second aspect of the present invention, in the ultrasonic flowmeter according to the first aspect, the transmitter / receiver holding unit is provided in each of the plurality of measurement tube components, and holds the ultrasonic transmitter / receiver in cooperation with each other. It has the characteristic in the place comprised.

  According to a third aspect of the present invention, in the ultrasonic flowmeter according to the second aspect, the total number of measuring tube constituents is two, the transducer holding part is integrally formed in the measuring tube constituents, and two measurements are made. It is characterized in that the tube structure is a molded product having the same shape.

  According to a fourth aspect of the present invention, in the ultrasonic flowmeter according to the third aspect, the concave and convex portions corresponding to each other are arranged symmetrically on the joint surface between the measuring tube constituents including the transducer holding portion. The convex portion of one measuring tube constituent is engaged with the concave portion of the other measuring tube constituent, and the concave portion of one measuring tube constituent is engaged with the convex portion of the other measuring tube constituent. It has the characteristic in having comprised.

  According to a fifth aspect of the present invention, in the ultrasonic flowmeter according to the third or fourth aspect of the present invention, the measurement tube structure including the transmitter / receiver holding portion is open to the joint surface between the measurement tube structures and transmits and receives the ultrasonic wave. A groove portion for accommodating an electric wire extending from the waver is formed, and the feature is that the opening of the groove portion is closed by joining the measuring tube constituent members.

  The invention of claim 6 is characterized in that, in the ultrasonic flowmeter according to any one of claims 1 to 5, the opening edge of the measuring tube is bulged inward to form a constricted portion.

  The invention of claim 7 is characterized in that, in the ultrasonic flowmeter of claim 6, the amount of projection of the constricted portion from the inner surface of the measuring tube is set to 0.05 to 0.5 [mm].

  The invention according to claim 8 is characterized in that in the ultrasonic flowmeter according to claim 6 or 7, chamfering is performed so that the opening edge of the measuring tube is rounded, and a curved surface by chamfering is continued in the constricted portion. Have.

  A ninth aspect of the invention is the ultrasonic flowmeter according to any one of the first to eighth aspects, wherein a cross section perpendicular to the fluid flow direction is flattened in an inner region of the measurement tube, and the inner surface of the measurement tube This is characterized in that groove portions are formed at both ends in the width direction.

  According to a tenth aspect of the present invention, in the ultrasonic flowmeter according to any one of the first to ninth aspects, the meter case is connected to a measurement tube housing room containing the measurement tube and one end of the measurement tube housing room. A fluid inflow passage and a fluid outflow passage communicated with the other end of the measuring tube housing chamber. The measuring tube is fitted to the inner surface of the measuring tube housing chamber, and the outer surface of the measuring tube is connected to the measuring tube. It is characterized in that an intermediate wall for isolating a region between the inner surface of the storage room and the fluid inflow path and the fluid outflow path is integrally formed.

  The invention according to claim 11 is characterized in that, in the ultrasonic flowmeter according to claim 12, an electric wire hole for passing an electric wire extending from the ultrasonic transducer is formed through the intermediate wall.

  The invention according to claim 12 is the ultrasonic flowmeter according to any one of claims 1 to 11, wherein the meter case is divided into a case main body and a case lid at one end of the measurement tube housing chamber, It is characterized in that the measuring tube is inserted and assembled inward from the opening of the measuring tube housing room opened to the dividing surface.

  A thirteenth aspect of the present invention is the ultrasonic flowmeter according to any one of the first to twelfth aspects, wherein the fluid inflow passage and the fluid outflow passage are formed in the case main body and are orthogonal to the measurement tube housing chamber. It is characterized by being open toward the side of the measuring tube in the accommodation room.

  According to a fourteenth aspect of the present invention, in the ultrasonic flowmeter according to any one of the first to thirteenth aspects, the measurement tube housing chamber has a circular cross section, and the transducer holder is circumferentially provided on the inner surface of the measurement tube housing chamber. It has the feature in the place which touches in three or more positions.

  A fifteenth aspect of the invention is the ultrasonic flowmeter according to any one of the first to fourteenth aspects, wherein the ultrasonic flowmeter is fitted inside the measurement pipe and changes a cross-sectional area perpendicular to the fluid flow direction in the measurement pipe. It is characterized by having an inner measuring tube.

  The ultrasonic flowmeter according to the invention of claim 16 is arranged to be separated from the meter case, the measurement pipe accommodated in the meter case, and the fluid flowing inside, the openings at both ends of the measurement pipe, A pair of ultrasonic transducers facing each other across the inner region of the measurement tube, and measuring the flow rate based on the propagation time of the ultrasonic waves transmitted and received between the pair of ultrasonic transducers The ultrasonic flowmeter is characterized in that a transmitter / receiver holding part for holding the ultrasonic transmitter / receiver at a position separated from the opening of the measuring tube is provided integrally with the measuring tube.

[Invention of Claim 1]
According to the invention according to claim 1 configured as described above, since the ultrasonic transducer is held in at least one of the plurality of measurement tube components constituting the measurement tube, the ultrasonic transducer and the measurement Variation in the distance to the tube and the distance between the ultrasonic transducers can be suppressed as compared with the conventional case. Thereby, the dispersion | variation in the performance between the products of an ultrasonic flowmeter can be suppressed compared with the past. Moreover, one assembly can be comprised with a measuring tube and a pair of ultrasonic transducer. Furthermore, the freedom degree of the internal shape of a measurement tube increases by comprising a measurement tube with a some measurement tube structure.

[Invention of claim 2]
According to the invention of claim 2, by assembling a plurality of measurement tube components, a plurality of transducer holders provided in the measurement tube components cooperate to hold the ultrasonic transducer. it can.

[Invention of claim 3]
According to the invention of claim 3, since the transducer holding part is integrally formed with the measuring tube constituting body, the number of parts is reduced and the labor of assembling can be saved as compared with the case where these are assembled as separate parts. In addition, since the two measuring tube components are molded products having the same shape, the molding dies can be shared, which is preferable in terms of manufacturing cost and component management.

[Invention of claim 4]
According to the fourth aspect of the present invention, it is possible to prevent misalignment of the plurality of measuring tube constituting bodies.

[Invention of claim 5]
According to invention of Claim 5, the electric wire extended from the ultrasonic transducer is inserted in a groove part from the open port open | released to the joint surface of the measurement pipe structure. And since the opening part of a groove part is closed by joining of measuring-tube structure bodies, the electric wire accommodated in the groove part can be protected.

[Inventions of Claims 6 and 7]
According to the invention of claim 6, the measurement accuracy can be improved. Here, it is preferable that the amount of protrusion of the constricted portion from the inner surface of the measuring tube is 0.05 to 0.5 [mm] (invention of claim 7).

[Invention of Claim 8]
According to invention of Claim 8, the flow of the fluid at the time of flowing in into a measurement pipe is stabilized.

[Invention of claim 9]
According to the ninth aspect of the invention, the fluid flow in the inner region of the measuring tube is stabilized.

[Invention of Claim 10]
According to the invention of claim 10, the fluid flows from the fluid inflow path into the measurement tube housing chamber and passes through the inside of the measurement tube. Then, the fluid that has passed through the inside of the measuring tube passes through the measuring tube housing chamber and is discharged from the fluid outflow path to the outside of the meter case. Here, the intermediate wall integrally formed with the measurement tube is fitted to the inner surface of the measurement tube housing chamber, thereby restricting the passage of fluid outside the measurement tube and the backlash of the measurement tube in the meter case. Can prevent sticking.

[Invention of Claim 11]
According to the eleventh aspect of the present invention, the pair of ultrasonic transducers are arranged separately in the measurement tube housing chamber into a region where the fluid inflow path communicates and a region where the fluid outflow path communicates. The wire of the ultrasonic transducer arranged in the region can be drawn into the other region through the wire hole. Thereby, the freedom degree of handling of an electric wire improves.

[Invention of Claim 12]
According to the twelfth aspect of the present invention, the measuring tube can be inserted and assembled from the opening of the measuring tube housing room opened to the dividing surface of the case body.

[Invention of Claim 13]
According to the invention of claim 13, since the fluid that has flowed into the measurement tube storage chamber collides with the side surface of the measurement tube before flowing into the measurement tube, the fluid flow state in the measurement tube has flowed into the measurement tube storage chamber. It becomes hard to be influenced by the state of the flow of time. Thereby, the flow of the fluid in a measuring tube can be stabilized.

[Invention of Claim 14]
According to the fourteenth aspect of the present invention, rattling of the measurement tube in the measurement tube accommodation room is prevented.

[Invention of Claim 15]
According to the invention of claim 15, by selecting whether or not the inner measurement tube is fitted inside the measurement tube, a specification for measuring a relatively small flow rate and / or flow rate and a relatively large flow rate are provided. And / or can be easily changed to specifications for measuring the flow rate.

[Invention of Claim 16]
According to the sixteenth aspect of the present invention, the pair of ultrasonic transducers is held by the transducer holding unit provided integrally with the measurement tube, so the distance between the ultrasonic transducer and the measurement tube, Variation in the distance between the ultrasonic transducers can be suppressed compared to the conventional case. Thereby, the dispersion | variation in the performance between the products of an ultrasonic flowmeter can be suppressed compared with the past.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
Reference numeral 10 in FIG. 1 is an “ultrasonic flow meter” of the present invention, and is attached in the middle of a gas pipe through which a gas as a fluid flows, for example. The ultrasonic flowmeter 10 includes a metering assembly 30 shown in FIG. 3 inside a meter case 20 shown in FIG.

  First, the meter case 20 will be described. The meter case 20 has a cylindrical structure with bottoms at both ends, and the inner region thereof corresponds to a measuring assembly housing chamber 23 having a cylindrical shape (the “measuring tube housing chamber” of the present invention). ). The meter case 20 can be divided into a case main body 21 and a case lid 22 at a portion near one end in the longitudinal direction (the left-right direction in FIG. 1). The case body 21 is open at one end in the longitudinal direction, and the opening 23 a is closed by a case lid 22 attached to one end of the case body 21. Here, the case lid 22 has a cylindrical structure with one end and opened to the opening 23a side of the case main body 21, and a flange 22d projects from the outer peripheral surface near the opening 22b to the side, On the outer peripheral surface between the flange 22d and the opening 22b, an O-ring 22c that is crushed and adhered to the inner peripheral surface of the opening 23a of the case body 21 is mounted.

  Further, two cylindrical portions 24, 24 stand up in the longitudinal direction from the upper surface of the case main body 21, and an inner region of these cylindrical portions 24, 24 communicates with the weighing assembly storage chamber 23. Of the cylindrical portions 24, 24, the inner region of one cylindrical portion 24 forms a gas inflow path 24 a (corresponding to the “fluid inflow path” of the present invention) for introducing gas into the measurement assembly housing chamber 23. The inner region of the other cylindrical portion 24 forms a gas outflow path 24b (corresponding to the “fluid outflow path” of the present invention) for discharging gas from the measuring assembly housing chamber 23. When a gas pipe (not shown) is connected to both the cylindrical portions 24, 24, the gas flows into the meter case 20 (measurement assembly storage chamber 23) as shown by the arrow in FIG. 1 flows from one end side to the other end side in the longitudinal direction (left-right direction in FIG. 1) in the measuring tube 31 of the measuring assembly 30 accommodated in the housing.

  Here, as shown in FIG. 1, the gas inflow passage 24 a and the gas outflow passage 24 b are orthogonal to the measuring assembly housing chamber 23 and open toward the side surface of the measuring tube 31 in the measuring assembly housing chamber 23. . As a result, the gas flowing into the measuring assembly housing chamber 23 collides with the side surface of the measuring tube 31, so the state of the gas flow in the measuring tube 31 is affected by the flow state when flowing into the measuring assembly housing chamber 23. It becomes difficult. In addition, since the gas flows for a certain distance along the side surface of the measurement tube 31 from the time when it hits the side surface of the measurement tube 31, the gas flow becomes more stable. Therefore, the flow in the measurement tube 31 can be stabilized. A circuit board (not shown) is attached to one side surface outside the meter case 20.

  The measuring assembly 30 includes a pair of ultrasonic sensors 32 and 32 (corresponding to the “ultrasonic transducer” of the present invention) at both ends of a measurement tube 31 having a cylindrical structure with both ends open. The measuring tube 31 extends from a position near one end in the longitudinal direction (left-right direction in FIG. 1) to a position near the other end in the meter case 20, and an inner region of the measuring tube 31 is a circular flow path 31a through which gas flows. (See FIG. 6B). In addition, a disc-shaped intermediate wall 36 protrudes laterally from the central portion in the axial direction of the measuring tube 31 (left-right direction in FIG. 3), and this intermediate wall 36 is formed on the inner surface of the measuring assembly housing chamber 23. It is mated. As shown in FIG. 1, the intermediate wall 36 is fitted to the inner surface of the portion between the gas inflow passage 24 a and the gas outflow passage 24 b of the measuring assembly housing chamber 23, and thereby the inner surface of the measuring assembly housing chamber 23. And the outer surface of the measurement tube 31 are opened in one opening 31b of the measurement tube 31 so that the inflow chamber 25 communicated with the gas inflow passage 24a and the other opening 31b of the measurement tube 31 is opened. Thus, it is isolated from the outflow chamber 26 communicating with the gas outflow passage 24b. The intermediate wall 36 prohibits the gas flowing into the measuring assembly housing chamber 23 from passing through the outside of the measuring tube 31 and being discharged from the measuring assembly housing chamber 23. That is, all the gas that has flowed into the inflow chamber 25 of the measuring assembly housing chamber 23 passes through the inside of the measuring tube 31 and flows into the outflow chamber 26. Here, by providing a seal member (for example, an O-ring) between the outer peripheral surface of the intermediate wall 36 and the inner surface of the measuring assembly housing chamber 23, the sealing property between the intermediate wall 36 and the inner surface of the measuring assembly housing chamber 23 can be improved. Can be increased.

  Furthermore, as shown in FIG. 5, a constricted portion 35 bulging inward over the entire circumference is formed at the opening edge of both openings 31b, 31b of the measuring tube 31. That is, the inner diameter of the flow path 31a of the measurement tube 31 is slightly reduced in diameter at the openings 31b and 31b. Thus, by providing the constricted part 35 in the openings 31b and 31b, the measurement accuracy of the gas flow velocity and / or flow rate can be improved. In the present embodiment, the inner diameter of the measuring tube 31 is 5.8 mm, and the amount of protrusion of the constricted portion 35 from the inner surface of the measuring tube 31 is 0.1 mm.

  Furthermore, as shown in FIG. 6A, the opening edge of the measuring tube 31 is chamfered to be rounded, and the curved surface resulting from this chamfering is continuous with the constricted portion 35. Thereby, the flow of gas when flowing into the measuring tube 31 from the opening 31b is stabilized.

  As shown in FIG. 1, the pair of ultrasonic sensors 32, 32 face each other with a predetermined distance from the openings 31 b, 31 b on both sides of the measurement tube 31, and face the axial direction of the measurement tube 31 (fluid Are arranged side by side in a direction parallel to the horizontal direction of FIG. The ultrasonic sensors 32 and 32 have a structure in which a metal cap 34 that covers a peripheral surface and a rear surface thereof is fitted and fixed to a flat cylindrical sensor main body 33, and a rear end portion of the cap 34 is laterally arranged. The flange 34a is formed by overhanging, and the front end surface of the sensor body 33 exposed from the cap 34 is a transmission / reception surface 33a. Further, electric wires extending from the ultrasonic sensors 32 are connected to a circuit board (not shown). Then, the time until the ultrasonic wave transmitted from one ultrasonic sensor 32 is received by the other ultrasonic sensor 32 (propagation time), and the ultrasonic wave transmitted from the other ultrasonic sensor 32 is converted to the one ultrasonic sensor 32. The difference from the time until reception (propagation time) is obtained, and the flow velocity / flow rate of the gas flowing in the measuring tube 31 is detected based on the difference. Here, the intermediate wall 36 is formed with a wire hole 36a passing through the inflow chamber 25 and the outflow chamber 26, and although not shown, for example, the wire of the ultrasonic sensor 32 arranged in the outflow chamber 26 is connected to the intermediate wall 36. The lead-in chamber 25 is drawn through the wire hole 36a. The electric wire hole 36a is closed by passing the electric wire. Here, the wire hole 36a can improve sealing performance by using a sealant (for example, a liquid sealant) or a seal member in combination.

  The ultrasonic sensors 32 and 32 are held by a plurality of sensor holding pieces 37 (corresponding to the “transmitter / receiver holding portion” of the present invention) extending from both ends of the measurement tube 31. The sensor holding pieces 37 are formed integrally with the measuring tube 31 and are provided at both ends of the measuring tube 31 at intervals of, for example, 90 degrees in the circumferential direction. These four sensor holding pieces 37 cooperate to hold one ultrasonic sensor 32.

  The sensor holding piece 37 has an axial direction of the measuring tube 31 (the left-right direction in FIG. 3) so that the outer portion of the wall body 37 a rising from the peripheral surface of the measuring tube 31 is separated from the openings 31 b and 31 b of the measuring tube 31. A locking claw 37 c is formed at the tip of the protruding portion 37 b protruding from the end of the measuring tube 31. The locking claw 37c is formed by recessing the inward surface of the protruding portion 37b into a groove shape, and the flange 34a of the ultrasonic sensor 32 is locked in the recessed groove 37d.

  By the way, the measuring tube 31 in which a plurality of sensor holding pieces 37 are integrally formed is composed of two measuring tube constructs 40 and 40 that are vertically divided in parallel to the axial direction (left and right direction in FIG. 3). Yes. Specifically, the measurement tube constituting bodies 40, 40 have a structure in which the measurement tube 30 is divided into two parts by a plane that bisects the two sensor holding pieces 37, 37 arranged 180 degrees apart in the plate thickness direction, It has the same shape. The measuring tube components 40, 40 are molded by pouring molten metal or synthetic resin into a molding die. Here, since the measuring tube constituents 40 and 40 have the same shape, the molding dies can be shared, which is preferable in terms of manufacturing cost and component management.

  As shown in FIGS. 4 and 5, a plurality of pin holes 42 penetrate through the holding piece divided bodies 41 and 41 obtained by dividing the sensor holding piece 37 in the plate thickness direction in the measuring tube constituting body 40. Is formed. When the joint surfaces of the two measuring tube constituting bodies 40, 40 are overlapped, the pin holes 42, 42 of the holding piece split bodies 41, 41 are aligned with each other, and fixed to the pin holes 42, 42, for example, not shown. By inserting the pin, the two measuring tube components 40, 40 are fixed together. Thereby, the measuring tube 31 in which the plurality of sensor holding pieces 37 are integrally formed is completed.

  As shown in FIGS. 4 and 5, in the measuring tube constituting body 40, an uneven engagement portion is formed on the joint surface of the intermediate wall divided bodies 43, 43 formed by dividing the intermediate wall 36 into two parts. Yes. Specifically, convex portions 44a and concave portions 44b are formed side by side on the joint surfaces of the intermediate wall divided bodies 43, 43 so as to sandwich the flow path 31a and to be orthogonal to the flow path 31a. Then, when the joint surfaces of the two measuring tube constituting bodies 40 and 40 are overlapped, the convex portion 44a of one measuring tube constituting body 40 engages with the concave portion 44b of the other measuring tube constituting body 40, and one measurement is performed. The concave portion 44b of the tube structure 40 engages with the convex portion 44a of the other measurement tube structure 40 in an uneven manner. Thereby, before fixing the two measuring tube components 40, 40 with the fixing pin, the fixing position can be positioned and the displacement is prevented.

  In addition, groove portions 43a and 43a that extend in parallel with the flow path 31a and open to the joint surface side are recessed in the joint surfaces of the intermediate wall divided bodies 43 and 43 outside the recess 44b. Then, when the joint surfaces of the two measuring tube constituting bodies 40, 40 are overlapped, the open ports of the groove portions 43a, 43a are closed by the joining surfaces of the mating measuring tube constituting bodies 40, 40, and the above-described electric wires A hole 36a is formed.

  This is the end of the description of the configuration of the ultrasonic flowmeter 10 of the present embodiment. By the way, the ultrasonic flowmeter 10 is assembled by the following procedures.

  First, the weighing assembly 30 is assembled. Specifically, the ultrasonic sensors 32 and 32 are temporarily held by the sensor holding piece 37 and the holding piece divided bodies 41 and 41 provided in one of the measurement tube constituting bodies 40. Moreover, the electric wire connected to one ultrasonic sensor 32 is previously inserted in the groove part 43a. Next, the joint surfaces of one measurement tube constituent body 40 temporarily holding the ultrasonic sensors 32 and 32 and the other other measurement pipe constituent body 40 are overlapped to form the convex portions 44a and the concave portions 44b. Combine. At this time, the ultrasonic sensors 32 and 32 are also held by the sensor holding piece 37 and the holding piece divided bodies 41 and 41 provided in the other measurement tube constituting body 40.

  In this state, a fixing pin is inserted into the pin hole 42 of the holding piece split bodies 41 and 41 which are overlapped, and the two measuring tube constituting bodies 40 and 40 are fixed integrally. As a result, the measurement tube 31, the sensor holding piece 37, and the intermediate wall 36 are completed, and a pair of ultrasonic sensors 32, 32 are fixedly arranged at positions facing the openings 31b, 31b of the measurement tube 31, The weighing assembly 30 is completed. That is, in the process of assembling the measurement tube 31 by assembling the two measurement tube components 40, 40 to each other, the plurality of sensor holding portions 37 integrally formed with the measurement tube components 40, 40 cooperate to provide the ultrasonic sensor 32. , 32 are held at positions away from both openings 31b, 31b of the measuring tube 31.

  Next, the completed weighing assembly 30 is attached to the meter case 20. Specifically, the measuring assembly 30 is inserted into the measuring assembly housing chamber 23 from the opening 23a of the case body 21, and one end of the measuring assembly 30 (specifically, the tip of the sensor holding piece 37) is stored in the measuring assembly. It is pushed in until it hits the end wall 23b on the back side of the chamber 23. Then, the intermediate wall 36 of the measurement assembly 30 is fitted to the inner surface of the measurement assembly storage chamber 23 at the intermediate portion between the two cylindrical portions 24 and 24 of the case body 21, and the measurement assembly storage chamber 23 sandwiches the intermediate wall 36. The inflow room 25 and the outflow room 26 are isolated from each other.

  Next, the opening end of the case lid 22 is fitted inside the opening 23a of the case main body 21, and the flange 22d of the case lid 22 is brought into contact with the peripheral edge of the opening 23a of the case main body 21. fix it with bolts. At this time, the end wall 22a on the back side of the case lid 22 abuts against the other end of the measuring assembly 30 (specifically, the tip of the sensor holding piece 37). That is, the measuring assembly 30 is sandwiched between the both end walls 22a and 23b of the meter case 20 in the longitudinal direction. This completes the assembly work of the ultrasonic flowmeter 10.

  On the other hand, when the weighing assembly 30 is removed, the bolt fixing the case lid 22 and the case main body 21 is removed, the case lid 22 is removed from the case main body 21, and the end of the weighing assembly 30 is pinched and the case main body 21 is removed. What is necessary is just to pull out from the opening part 23a.

  As described above, according to the present embodiment, the pair of ultrasonic sensors 32 and 32 are held by the sensor holding piece 37 integrally formed with the measurement tube 31 (the plurality of measurement tube components 40 and 40). Variations in the distance between the ultrasonic sensors 32, 32 and the openings 31b, 31b of the measurement tube 31 and the distance between the ultrasonic sensors 32, 32 are suppressed more than before, and the performance between products in the ultrasonic flowmeter 10 (specifically Specifically, variation in measurement accuracy) can be suppressed as compared with the conventional case. Further, since the measuring tube 31 is composed of two measuring tube constructs 40 and 40 that are vertically divided in parallel to the axial direction, the constricted portion 35 is formed at the opening edge of the measuring tube 31 as described above. For example, the degree of freedom of the shape of the internal region (flow path 31a) of the measurement tube 31 is increased.

  Further, the intermediate wall 36 integrally formed with the measuring tube 31 is fitted to the inner surface of the measuring assembly housing chamber 23, and the front end portions of the sensor holding portion 37 integrally formed with the measuring tube 31 (both ends of the measuring assembly 30). However, since it contacts the end walls 22a and 23b opposed to each other in the longitudinal direction of the meter case 20, rattling of the measuring tube 31 (the measuring assembly 30) in the measuring assembly housing chamber 23 is prevented. Furthermore, one assembly can be constituted by the three parts of the measuring tube 31 and the pair of ultrasonic sensors 32, 32, and the measurement accuracy test of the ultrasonic flowmeter 10 can be easily performed.

  Here, since the conventional ultrasonic flowmeter is configured to fix the measurement tube and the ultrasonic sensor to the holder provided inside the meter case, the attachment of the measurement tube and the ultrasonic sensor is referred to as the inside of the meter case. It could only be done in a small space, and the installation work was inefficient. On the other hand, according to the present embodiment, the ultrasonic sensor 32, 32 is assembled to the measuring tube 31 to form one measuring assembly 30, and the measuring assembly 30 is inserted into the meter case 20 and assembled. Compared with the assembly work becomes easier.

[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 other than the following can be made without departing from the scope of the invention. It can be changed and implemented.
(1) In the above embodiment, gas is exemplified as the fluid to be measured by the ultrasonic flowmeter 10, but a liquid may be used.

(2) In the above-described embodiment, one ultrasonic sensor 32 is cooperatively held by the four sensor holding pieces 37, but may be held by one sensor holding piece, or a plurality other than four These sensor holding pieces may be held together.

(3) In the above embodiment, the measurement tube 31 is composed of the two measurement tube components 40, 40, but may be composed of three or more measurement tube components.

(4) In the above embodiment, in the process of assembling the measurement tube 31, the ultrasonic sensors 32, 32 are held by the sensor holding piece 37, but the measurement is performed by assembling the two measurement tube components 40, 40. The ultrasonic sensors 32 and 32 may be held by the sensor holding piece 37 after the tube 31 is assembled. At this time, the sensor holding piece 37 is slidably contacted with the flange 34a of the ultrasonic sensors 32, 32 and elastically deformed outward, and is restored to the original shape when the ultrasonic sensors 32, 32 reach the proper attachment positions. What is necessary is just to comprise so that the flange 34a may latch to the depression groove 37d.

(5) In the above embodiment, the flow path 31a of the measurement tube 31 has a circular cross section. For example, a cross section perpendicular to the fluid flow direction of the flow path 51 is a width dimension as in the measurement tube 50 shown in FIG. As shown in FIG. 8 (B), both ends in the width direction of the inner surface of the measuring tube 50 (left and right direction in FIG. 8 (B)) The groove portions 51a and 51a may be formed.

  Specifically, the grooves 51 a and 51 a have a shape in which both end portions in the width direction of the inner surface of the measurement tube 50 are bulged outwardly in an arc shape, and the diameter of the arc is the width direction of the measurement tube 50. It is larger than the height of the flow path 51 in the center (the length in the vertical direction in FIG. 8B). Further, in the openings 50b and 50b of the measuring tube 50, the inner surface of the groove 51a bulges inward, and the flow path 51 in the vicinity of the openings 50b and 50b of the measuring tube 50 is shown in FIG. The cross-sectional shape is oval. By making the flow path 51 have the above structure, the flow of fluid passing through the flow path 51 can be stabilized.

  Although not shown in FIGS. 7 and 8, sensor holding pieces for holding the ultrasonic sensor are integrally extended from both ends of the measurement tube 50 in the same manner as in the above embodiment, and the length of the measurement tube 50 is extended. From the intermediate portion in the direction, an intermediate wall that fits into the inner surface of the measuring assembly housing chamber projects laterally. Furthermore, the measuring tube 50 may be divided into two measuring tube components 52, 52 having the same shape, for example, at an intermediate portion in the flat direction.

(6) As shown in FIG. 9, an inner measurement tube 60 having a flow channel 60a having a smaller diameter than the flow channel 31a of the measurement tube 31 is detachably fitted into the measurement tube 31 (flow channel 31a). Thus, all the fluid flowing through the measurement tube 31 may pass through the flow path 60a of the inner measurement tube 60. If it does in this way, it will become possible to change the cross-sectional area orthogonal to the flow direction of the flow path through which gas flows into two different large and small cross-sectional areas. That is, by fitting the inner measurement tube 60 to the measurement tube 31, the cross-sectional area of the flow path is made relatively small, and the ultrasonic flowmeter 10 is set to a specification for measuring a relatively small flow velocity and / or flow rate. By not attaching the inner measurement tube 60 to the measurement tube 31, the cross-sectional area of the flow path is made relatively large, and the ultrasonic flowmeter 10 is easily changed to specifications for measuring a relatively large flow velocity and / or flow rate. be able to. Thereby, the ultrasonic flowmeter 10 can be accurately measured over a wider flow velocity range and / or flow rate range.

(7) In the above embodiment, the constricted portion 35 is formed at the opening edge of the measuring tube 31, but the inner surface of the middle portion in the longitudinal direction of the measuring tube 31 is bulged inward and in the middle of the flow path 31 a. You may form the shrinkage | contraction part in which the cross-sectional area became small.

(8) In the above embodiment, the peripheral surface of the intermediate wall 36 and both end portions of the sensor holding piece 37 are brought into contact with the inner surface of the measuring assembly housing chamber 23 to fix the measuring assembly 30 in the measuring assembly housing chamber 23. However, the sensor holding pieces 37 provided at both ends of the measuring assembly 30 may be fixed by contacting the inner surface of the measuring assembly housing chamber 23 at three or more positions in the circumferential direction.

(9) In the above-described embodiment, the pair of ultrasonic sensors 32 and 32 are arranged side by side in a direction parallel to the flow direction of the fluid (gas) (the axial direction of the measurement tube 31). May be arranged side by side in a direction that crosses diagonally.

1 is a side sectional view of an ultrasonic flowmeter according to an embodiment of the present invention. Disassembled perspective view of meter case Side view of weighing assembly Disassembled perspective view of weighing assembly Plan view of measuring tube structure (A) Side sectional view at the opening of the measuring tube (B) Front sectional view at the center of the measuring tube A perspective view of a measuring tube according to another embodiment (5) (A) Front view of measuring tube (B) Front sectional view at the center of the measuring tube Front sectional view of a measurement tube according to another embodiment (6)

Explanation of symbols

10 Ultrasonic flow meter 20 Meter case 21 Case body 22 Case lid 23 Measuring assembly storage chamber (measuring tube storage chamber)
24a Gas inflow path (fluid inflow path)
24b Gas outflow path (fluid outflow path)
30 Weighing assembly 31, 50 Measuring tube 32 Ultrasonic sensor (ultrasonic transducer)
36 Intermediate wall 36a Electric wire hole 37 Sensor holding piece (transmitter / receiver holding part)
40, 52 Measuring tube structure 43a Groove 44a Convex 44b Concave 51a Groove 60 Inner measuring tube

Claims (16)

A meter case, a measurement tube that is accommodated in the meter case, and a fluid flows inside, and is arranged away from the openings at both ends of the measurement tube, facing each other across the inner region of the measurement tube An ultrasonic flowmeter comprising a pair of ultrasonic transducers and measuring a flow rate based on a propagation time of ultrasonic waves transmitted and received between the pair of ultrasonic transducers;
A plurality of measuring tube constituents formed by vertically dividing the measuring tube is assembled to constitute the measuring tube, and the ultrasonic transducer is connected to the opening of the measuring tube in at least one of the measuring tube constituents. An ultrasonic flowmeter characterized in that a transmitter / receiver holding portion for holding at a position separated from the head is integrally provided.   2. The transmitter / receiver holding unit is provided in each of the plurality of measurement tube components, and is configured to hold the ultrasonic transmitter / receiver in cooperation with each other. Ultrasonic flow meter.   The total number of the measuring tube constituents is two, the transducer holding part is formed integrally with the measuring tube constituents, and the two measuring tube constituents are formed into the same shape. The ultrasonic flowmeter according to claim 2.   Corresponding concave portions and convex portions are symmetrically arranged on the joint surfaces of the measurement tube constituent bodies including the transducer holding portion, and the convex portion of one of the measurement pipe constituent bodies is the other measurement. The concave and convex engagement with the concave portion of the tube structure is configured such that the concave portion of one of the measurement tube structural members engages with the convex and concave portion of the other measurement tube structural body. Item 4. The ultrasonic flowmeter according to Item 3.   The measurement tube structure including the transducer holding part is formed with a groove portion that opens to a joint surface between the measurement tube structure members and accommodates an electric wire extending from the ultrasonic transducer, 5. The ultrasonic flowmeter according to claim 3, wherein the opening is closed by joining the measuring tube constituent members.   6. The ultrasonic flowmeter according to claim 1, wherein a constricted portion is formed by bulging an opening edge of the measurement tube inward.   The ultrasonic flowmeter according to claim 6, wherein an amount of protrusion of the constricted portion from the inner surface of the measuring tube is 0.05 to 0.5 [mm].   The ultrasonic flowmeter according to claim 6 or 7, wherein chamfering is performed so that an opening edge of the measuring tube is rounded, and a curved surface by the chamfering is made continuous with the constricted portion.   The cross section perpendicular to the fluid flow direction in the inner region of the measurement tube is flattened, and grooves are formed at both ends in the width direction on the inner surface of the measurement tube. The ultrasonic flowmeter according to Crab. The meter case includes a measuring tube housing chamber that houses the measuring tube, a fluid inflow passage that communicates with one end of the measuring tube housing chamber, and a fluid outflow that communicates with the other end of the measuring tube housing chamber. Road and
The measurement tube is fitted to the inner surface of the measurement tube storage chamber, and a region between the outer surface of the measurement tube and the inner surface of the measurement tube storage chamber is between the fluid inflow path and the fluid outflow path. The ultrasonic flowmeter according to claim 1, wherein an intermediate wall for isolating is formed integrally.   The ultrasonic flowmeter according to claim 12, wherein a wire hole for passing an electric wire extending from the ultrasonic transducer is formed through the intermediate wall.   The meter case is divided into a case main body and a case lid at one end of the measurement tube storage chamber, and the measurement tube is inserted and assembled inside the opening of the measurement tube storage chamber opened to the divided surface. The ultrasonic flowmeter according to claim 1, wherein the ultrasonic flowmeter is provided.   The fluid inflow path and the fluid outflow path are formed in the case body, are orthogonal to the measurement tube accommodation chamber, and open toward the side surface of the measurement tube in the measurement tube accommodation chamber. The ultrasonic flowmeter according to claim 1.   14. The measurement tube housing chamber has a circular cross section, and the transducer holding part is in contact with the inner surface of the measurement tube housing chamber at three or more positions in the circumferential direction. The ultrasonic flowmeter described in 1.   15. The inner measurement tube according to claim 1, further comprising an inner measurement tube that is fitted inside the measurement tube and changes a cross-sectional area perpendicular to a fluid flow direction in the measurement tube. Ultrasonic flow meter. A meter case, a measurement tube that is accommodated in the meter case, and a fluid flows inside, and is arranged away from the openings at both ends of the measurement tube, facing each other across the inner region of the measurement tube An ultrasonic flowmeter comprising a pair of ultrasonic transducers and measuring a flow rate based on a propagation time of ultrasonic waves transmitted and received between the pair of ultrasonic transducers;
An ultrasonic flowmeter characterized in that a transducer holding part for holding the ultrasonic transducer at a position separated from the opening of the measurement tube is provided integrally with the measurement tube.

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