Ultrasonic flowmeter

Abstract

An ultrasonic flow meter is provided with: a measurement flow path (3) in which a fluid to be measured flows, the flow path having a rectangular cross-section; one or more partition plates (8) that divide the measurement flow path (3) into a plurality of layered flow paths; and a pair of ultrasonic sensors disposed upstream and downstream in the layered flow path and capable of transmitting and receiving ultrasonic signals. In addition, the ultrasonic flow meter includes a flow rate measuring section that detects a flow rate of the fluid to be measured based on an ultrasonic signal transmitted from the ultrasonic sensor at a transmission time when the fluid to be measured is transmitted to the ultrasonic sensor reception signal. Furthermore, the measurement flow path (3) and the partition plate (8) are integrally molded, and the partition plate (8) is formed in a shape that becomes thinner toward the inlet side of the measurement flow path (3) and the outlet side of the measurement flow path (3) from the portion having the maximum thickness.

Description

[0001] This application is a divisional application of the PCT application PCT / JP2019 / 027783 filed by the applicant Panasonic Intellectual Property Management Co., Ltd. on July 12, 2019, which entered the national stage on February 4, 2021, with application number 201980052050.5 and invention name “Ultrasonic Flow Meter”. Technical Field

[0002] The present invention relates to an ultrasonic flow meter which measures flow by dividing a measuring flow path into multi-layer flow paths by a partition plate. Background Art

[0003] Conventionally, there are such ultrasonic flow meters as Figure 6 As shown in the figure, the ultrasonic flow meter is composed of a measuring flow path 101, a plurality of partition plates 102, and a rolled-in flow suppression sheet 103 as independent components. The measuring flow path 101 has a component insertion port 106. After the plurality of partition plates 102 are inserted into the measuring flow path 101 from the component insertion port 106 at a predetermined angle, the component insertion port 106 is covered with the rolled-in flow suppression sheet 103. Then, the ultrasonic sensor mounting block 104 is fixed to the measuring flow path 101 by heat welding or the like to block the component insertion port 106, and a pair of ultrasonic sensors 105a and 105b are mounted on the ultrasonic sensor mounting block 104, thereby Figure 6 The ultrasonic flowmeter shown has a structure in which the measured fluid does not leak. In addition, the entrained flow suppression sheet 103 is provided with openings 103a and 103b for ultrasonic waves to pass through (for example, see Patent Document 1). In addition, the partition plate 102 is provided in the measuring flow path 101 for the purpose of making the flow velocity distribution of the fluid flowing in the measuring flow path 101 uniform.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-215060 Summary of the invention

[0007] However, the conventional ultrasonic flowmeter described in Patent Document 1 has problems such as a large number of components and high cost.

[0008] In addition, the partition plate 102 is formed by punching a metal plate with a die, but burrs and warping are generated during the forming process, resulting in different states between the front and back surfaces. Therefore, in order to improve the measurement accuracy, the front and back surfaces need to be consistent, and a design is required to identify the front and back surfaces of the partition plate 102.

[0009] The present invention reduces costs compared to conventional structures by integrally forming the measuring flow path and the partition plate, and utilizes the draft angle of the mold generated on the partition plate as the measuring flow path and the partition plate are integrally formed to suppress undesirable situations such as deviation in the traveling direction of the sound wave reflected on the partition plate or fluid peeling off at the end of the partition plate, which causes deviation in the flow of the measured fluid. Furthermore, an ultrasonic flow meter is provided that can improve the deviation in measurement caused by the disturbance of the received signal waveform generated by the undesirable situation.

[0010] The ultrasonic flowmeter disclosed in the present invention includes: a measuring flow path, the cross-section of which is rectangular for the flow of the measured fluid; one or more partition plates, which divide the measuring flow path into a plurality of layered flow paths; and a pair of ultrasonic sensors, which are arranged upstream and downstream on the layered flow path and can send and receive ultrasonic signals. In addition, the ultrasonic flowmeter disclosed in the present invention includes a flow measurement unit, which detects the flow rate of the measured fluid based on the transmission time from the ultrasonic signal sent from one ultrasonic sensor to the transmission time from the measured fluid to the reception time of the signal from another ultrasonic sensor. Moreover, the measuring flow path is integrally formed with the partition plate, and the partition plate is set to a shape that becomes thinner from the portion with the maximum thickness toward the inlet side and the outlet side of the measuring flow path.

[0011] According to this configuration, the ultrasonic flowmeter of the present disclosure can reduce the number of components and component costs compared to the related art, and can improve measurement variations caused by separation of the measured fluid at the end of the partition plate and flow disturbance of the measured fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a cross-sectional view of the ultrasonic flow meter according to the first embodiment.

[0013] Figure 2 It is a perspective view of the measurement flow path of the ultrasonic flow meter according to the first embodiment.

[0014] Figure 3A yes Figure 2 3A-3A sectional view of.

[0015] Figure 3B yes Figure 3A An enlarged view of section 3B.

[0016] Figure 4 It is a cross-sectional view of the ultrasonic flow meter according to the second embodiment, taken in a direction perpendicular to the partition plate.

[0017] Figure 5 It is a cross-sectional view of the ultrasonic flow meter according to the third embodiment, taken in a direction perpendicular to the partition plate.

[0018] Figure 6 This is an exploded perspective view of a conventional ultrasonic flow meter. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments will be described with reference to the drawings.

[0020] (First embodiment)

[0021] Figure 1 It is a cross-sectional view of the ultrasonic flow meter according to the first embodiment. Figure 2 It is a perspective view of the measurement flow path of the ultrasonic flow meter according to the first embodiment. Figure 3A yes Figure 2 3A-3A sectional view of. Figure 3B yes Figure 3A An enlarged view of section 3B.

[0022] like Figure 1 and Figure 3A As shown, the measuring flow path 3 that allows the measured fluid to flow from the measuring flow path inlet 9 to the measuring flow path outlet 10 is a pipe that circulates the measured fluid, and is divided into three layered flow paths 3a, 3b, and 3c by two partition plates 8. Openings 6a and 6b that transmit ultrasonic waves are formed on the upper surface 4 of the measuring flow path in a manner that transmits and receives ultrasonic waves obliquely relative to the measuring flow path 3, and ultrasonic sensors 1a and 1b are fixed to mounting portions 2a and 2b in a manner that ultrasonic waves are reflected on the bottom surface 5 of the measuring flow path and pass through transmission paths P1 and P2. The flow measurement unit 7 calculates the flow rate based on the transmission time of the ultrasonic waves between the ultrasonic sensors 1a and 1b.

[0023] Moreover, if Figure 2 As shown, the measuring flow path 3, the partition plate 8, and the mounting parts 2a and 2b are integrally molded from resin. This can reduce the number of components and reduce costs compared to conventional ultrasonic flow meters.

[0024] Next, use Figure 3A , Figure 3B , the structure of the partition plate 8 which is a feature of the present application will be described in detail.

[0025] The shape of the partition plate 8 in the present embodiment aims to improve the accuracy of flow rate measurement when the measurement flow path 3 and the partition plate 8 are integrally formed.

[0026] Therefore, the partition plate 8 is formed in a shape that gradually becomes thinner from the portion 8 a having the largest thickness toward the measurement flow path inlet 9 and the measurement flow path outlet 10 of the measurement flow path 3 toward the top ends 11 and 12 of the partition plate 8 .

[0027] Due to the dimensional accuracy of resin molding, the partition plate 8 needs to be thick to a certain extent. However, the thicker the end 8d of the partition plate 8 located on the side of the measuring flow path inlet 9 is, the easier it is for the measured fluid to peel off. Therefore, the movement of the measured fluid in the area C of the measuring flow path 3 that transmits ultrasonic waves becomes unstable. Therefore, in this embodiment, by providing the sharp portions 8b and 8c that make the thickness of the partition plate 8 become thinner from the portion 8a with the maximum thickness toward the top ends 11 and 12 of the partition plate 8, it is possible to suppress the peeling of the measured fluid and stabilize the flow measurement.

[0028] In addition, the partition plate 8 forms a surface parallel to the flow direction of the fluid to be measured and the radiation direction of the sound of the ultrasonic sensors 1a and 1b in the region C where the ultrasonic wave propagates.

[0029] That is, in order to suppress the turbulence of the flow of the measured fluid to the greatest extent, the cross-sectional shape of the partition plate 8 is most suitable to be entirely streamlined. However, in the area C where the ultrasonic waves sent and received by the ultrasonic sensors 1a and 1b are transmitted, the ultrasonic waves are reflected on the surface of the partition plate 8. Therefore, when the reflecting surface is a curved surface, the reflection direction of the sound wave is different depending on where the sound wave is reflected on the partition plate 8, and the received signal waveform finally obtained becomes unstable. Therefore, in the area C where the ultrasonic wave is transmitted, by forming the partition plate 8 with a surface that is as flat as possible and parallel to the flow direction of the measured fluid and the radiation direction of the sound of the ultrasonic sensors 1a and 1b, the deviation of the received signal waveform is reduced compared with the case where the surface of the partition plate 8 is inclined, and a more stable measurement can be performed.

[0030] In addition, if Figure 3B As shown, the tip 11 of the partition plate 8 on the measurement flow path inlet 9 side may be formed as a curved surface. Furthermore, the tip 12 of the partition plate 8 on the measurement flow path outlet 10 side may also be formed as a curved surface.

[0031] When the fluid is separated by a plate-like rigid body, the teardrop-shaped cross-sectional shape with a smooth front edge and a tapered rear edge of the rigid body minimizes fluid separation and resistance. However, in actual gas meters using ultrasonic flowmeters, backflow also occurs. Therefore, in the case of a shape with a tapered rear edge, backflow occurs, and when the inflow angle of the measured fluid deviates from the angle of the partition plate, the measured fluid is separated by the rear edge. Therefore, the flow in the area where the ultrasonic wave measured by the ultrasonic sensor is transmitted is turbulent, and the measured value of the flow measurement in the forward flow and reverse flow may differ.

[0032] In addition, when the top of the partition plate 8 is set at an acute angle, insufficient filling occurs during molding, and the top shape is uneven, which may also cause turbulence in the flow of the measured fluid. Therefore, by setting the tops 11 and 12 on both sides of the measurement flow path inlet 9 side and the measurement flow path outlet 10 side of the partition plate 8 as curved surfaces, more stable flow measurement can be performed.

[0033] (Second embodiment)

[0034] Figure 4 2 is a cross-sectional view of the ultrasonic flowmeter according to the second embodiment in a direction perpendicular to the partition plate. Figure 1 same.

[0035] In an ultrasonic flow meter, in the case of downstream flow, it is important to reduce fluid peeling mainly in the area measured by the ultrasonic sensors 1a and 1b. In the present embodiment, the portion 13a of the partition plate 13 where the maximum thickness occurs is not the center point of the partition plate 13, but is closer to the trailing edge (on the measuring flow path outlet 10 side) than to the leading edge (on the measuring flow path inlet 9 side).

[0036] With this configuration, the ultrasonic flow meter of the present embodiment can suppress separation of the fluid in the region where ultrasonic waves are measured in the case of downstream flow, and can perform more stable measurement.

[0037] In addition, in the measurement area of ​​the ultrasonic sensors 1a and 1b (the area where ultrasonic waves are transmitted), if the surface of the partition plate 13 has a curved surface, the reflection direction of the sound wave will differ depending on where on the partition plate 13 the sound wave is reflected, and the received signal waveform becomes unstable. Therefore, it is also possible to avoid setting curved surfaces in the measurement area of ​​the ultrasonic sensors 1a and 1b as much as possible, and instead use a flat surface.

[0038] (Third embodiment)

[0039] Figure 5 14 is a cross-sectional view of the ultrasonic flowmeter according to the third embodiment in a direction perpendicular to the partition plate. Figure 1 same.

[0040] In the present embodiment, the inner walls 15d and 15e of the measuring flow path 15 that are parallel to the partition plate 14 are provided with slopes symmetrical to the slope of the opposing partition plate 14. That is, in order to make the three layered flow paths 15a, 15b, and 15c formed by dividing the measuring flow path 15 by two partition plates 14 have the same shape, the inner walls 15d and 15e of the flow paths are also provided with the same slope as the draft slope θ1 provided on the partition plate 14.

[0041] If the shapes of the flow areas of the measured fluids in the laminar flow paths are different, the flow velocity distribution and pressure loss of each layer will be different, and the flow velocity ratio of each layer will be far from a uniform ratio. In this case, if the temperature or gas type changes, the flow velocity ratio will also change, so it is difficult to correct it using software, which will cause errors in the measured flow rate. In contrast, according to this embodiment, the shapes of the laminar flow paths 15a, 15b, and 15c are made the same, so that the flow velocity ratio of each layer is uniform, and more stable flow measurement can be performed.

[0042] As described above, according to the present disclosure, the cost is reduced compared with the previous structure by integrally forming the measuring flow path and the partition plate, and the draft angle of the mold generated on the partition plate due to the integrally forming of the measuring flow path and the partition plate is set. According to this structure, it is possible to improve the measurement deviation caused by the disturbance of the received signal waveform due to the deviation of the traveling direction of the sound wave reflected on the partition plate or the deviation of the flow of the measured fluid due to the separation of the fluid at the end of the partition plate.

[0043] In addition, in the figures used in the description of the above embodiment, the inclination of the partition plate is depicted as large for easy understanding, but the draft angle of the actual mold is about 0.3°. In addition, the partition plate is set as two for description, but it goes without saying that it can also be one or three or more.

[0044] As described above, the first disclosed ultrasonic flowmeter includes: a measuring flow path, the cross-section of which is rectangular for the flow of the measured fluid; one or more partition plates, which divide the measuring flow path into a plurality of layered flow paths; and a pair of ultrasonic sensors, which are arranged upstream and downstream on the layered flow path and can transmit and receive ultrasonic signals. In addition, the ultrasonic flowmeter disclosed in the present invention includes a flow measurement unit, which detects the flow rate of the measured fluid based on the transmission time of the ultrasonic signal sent from one ultrasonic sensor to the measured fluid to the other ultrasonic sensor receiving the signal. Moreover, the measuring flow path is integrally formed with the partition plate, and the partition plate is set to a shape that gradually becomes thinner from the portion with the maximum thickness toward the measuring flow path inlet side and the measuring flow path outlet side.

[0045] According to this configuration, the ultrasonic flowmeter of the first disclosure can reduce the number of components and component costs compared to the related art, and improve measurement variations caused by separation of the measured fluid at the end of the partition plate and flow disturbance of the measured fluid.

[0046] The ultrasonic flowmeter disclosed in the second aspect is particularly based on the first aspect, and the portion with the maximum thickness is composed of a surface parallel to the flow direction of the measured fluid and the radiation direction of the sound of the ultrasonic sensor, and includes at least a portion of the area that transmits the sound waves sent by the ultrasonic sensor.

[0047] According to this configuration, the ultrasonic flowmeter of the second disclosure makes the propagation of sound waves and the flow of the fluid to be measured in the measurement area measured by ultrasonic waves uniform, thereby enabling more stable measurement.

[0048] The ultrasonic flowmeter according to the third disclosure may be particularly based on the first disclosure, wherein at least a tip end of the partition plate on the measuring flow path inlet side may be formed of a curved surface.

[0049] According to this structure, the ultrasonic flowmeter of the third disclosure can suppress underfilling at the top end of the partition plate during molding and make the end of the partition plate thinner, thereby making a shape that suppresses turbulence in the flow of the measured fluid and performing more stable measurement.

[0050] In the ultrasonic flowmeter according to the fourth disclosure, in particular, in the second disclosure, at least a tip end of the partition plate on the measuring flow path inlet side may be formed of a curved surface.

[0051] According to this structure, the ultrasonic flowmeter of the fourth disclosure can suppress underfilling at the top end of the partition plate during molding and make the end of the partition plate thinner, thereby forming a shape that suppresses turbulence in the flow of the measured fluid and performing more stable measurement.

[0052] The ultrasonic flowmeter disclosed in the fifth aspect is particularly in any one of the first to fourth aspects, wherein a portion of the partition plate having the largest thickness is closer to the measuring flow path outlet side when viewed from the center point of the transmission path in the measuring flow path of the ultrasonic sensor.

[0053] According to this configuration, the ultrasonic flow meter of the fifth disclosure can suppress separation of the fluid in the region where the ultrasonic wave is measured in the case of downstream flow, and can perform more stable measurement.

[0054] The ultrasonic flow meter of the sixth disclosure may be particularly any one of the first to fourth disclosures, wherein the measurement flow path may have a slope matching the shape of the partition plate so that the shapes of the plurality of laminar flow paths are the same.

[0055] Since the shapes of the laminar flow paths are the same, the flow velocity ratio between the laminar flow paths is uniform, enabling more stable flow measurement.

[0056] The ultrasonic flow meter of the seventh disclosure may be particularly configured according to the fifth disclosure, wherein the plurality of laminar flow paths of the measuring flow path may have a slope matching the shape of the partition plate so that the shapes of the plurality of laminar flow paths are the same.

[0057] Since the shapes of the laminar flow paths are the same, the flow velocity ratio between the laminar flow paths is uniform, enabling more stable flow measurement.

[0058] The ultrasonic flowmeter of the eighth disclosure may be particularly any one of the first to fourth disclosures, and further include a sensor mounting portion for mounting the ultrasonic sensor, and the measurement flow path, the partition plate, and the sensor mounting portion may be integrally formed.

[0059] According to this configuration, it is possible to reduce the material cost and assembly man-hours required for the ultrasonic sensor mounting block.

[0060] The ultrasonic flowmeter disclosed in the ninth aspect is particularly based on the fifth aspect, and may further include a sensor mounting portion for mounting the ultrasonic sensor, and the measurement flow path, the partition plate, and the sensor mounting portion may be integrally formed.

[0061] According to this configuration, it is possible to reduce the material cost and assembly man-hours required for the ultrasonic sensor mounting block.

[0062] The ultrasonic flowmeter of the tenth disclosure may be particularly based on the sixth disclosure, and further include a sensor mounting portion for mounting the ultrasonic sensor, and the measurement flow path, the partition plate, and the sensor mounting portion may be integrally formed.

[0063] According to this configuration, it is possible to reduce the material cost and assembly man-hours required for the ultrasonic sensor mounting block.

[0064] The ultrasonic flowmeter of the eleventh disclosure may be particularly based on the seventh disclosure, and further include a sensor mounting portion for mounting the ultrasonic sensor, and the measurement flow path, the partition plate, and the sensor mounting portion may be integrally formed.

[0065] According to this configuration, it is possible to reduce the material cost and assembly man-hours required for the ultrasonic sensor mounting block.

[0066] Industrial Applicability

[0067] As described above, the ultrasonic flowmeter disclosed in the present invention can reduce the cost of conventional components and improve the variation in thickness measurement caused by separation of the measured fluid at the end of the partition plate and flow disturbance of the measured fluid, and can therefore also be applied to gas meters and the like.

[0068] Description of Reference Numerals

[0069] 1a, 1b, ultrasonic sensor; 2a, 2b, mounting portion; 3, 15, measuring flow path; 3a, 3b, 3c, 15a, 15b, 15c, layered flow path; 6a, 6b, opening; 7, flow measurement portion; 8, 13, 14, partition plate; 8a, 13a, portion having maximum thickness; 9, measuring flow path inlet; 10, measuring flow path outlet; 11, 12, top end.

Claims

1. An ultrasonic flow meter, wherein: The ultrasonic flow meter includes: A measuring flow path, wherein the cross section of the flow path for the measured fluid to flow is rectangular; one or more partition plates, which divide the measurement flow path into a plurality of laminar flow paths; a pair of ultrasonic sensors disposed upstream and downstream of the laminar flow path and capable of transmitting and receiving ultrasonic signals; and a flow measurement unit for detecting the flow rate of the fluid to be measured based on the transmission time from the ultrasonic signal transmitted from one of the ultrasonic sensors to the transmission time from the fluid to be measured to the reception time of the signal from the other ultrasonic sensor, The measuring flow path is integrally formed with the partition plate, and the partition plate is formed in a shape that becomes thinner from a portion having the largest thickness toward a measuring flow path inlet side and a measuring flow path outlet side. A portion of the partition plate having the maximum thickness is located close to an outlet side of the measurement flow path when viewed from a center point of a transmission path in the measurement flow path of the ultrasonic sensor.

2. The ultrasonic flowmeter according to claim 1, characterized in that: The portion having the maximum thickness is formed by a surface parallel to the flow direction of the fluid to be measured and the radiation direction of the sound of the ultrasonic sensor, and includes at least a part of the region where the sound waves emitted by the ultrasonic sensor are transmitted.

3. The ultrasonic flow meter according to claim 1, characterized in that: At least a tip end of the partition plate on the measurement flow path inlet side is formed of a curved surface.

4. The ultrasonic flow meter according to claim 2, characterized in that: At least a tip end of the partition plate on the measurement flow path inlet side is formed of a curved surface.

5. The ultrasonic flowmeter according to any one of claims 1 to 4, characterized in that: The ultrasonic flow meter also includes a sensor mounting portion, which is used to mount the ultrasonic sensor. The measuring flow path, the partition plate, and the sensor mounting portion are integrally formed.

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