JP2009276227A - Flowmeter, and line for flow-rate measurement used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a route for sweeping equally a flow-rate distribution in a pipe section, and to accurately perform flow rate measurement reflecting the flow-rate distribution in the pipe section. <P>SOLUTION: This flowmeter 1 has a line 3 for measuring the flow rate formed by combining the first curved line part 36 and the second curved line part 37, each having a mutually reverse curved swelling direction. When a fluid passes the first curved line part 36 and the second curved line part 37, a flow-rate distribution in an axial section receives forcibly each mutually reverse deflection. A propagation route SW, extending over both curved line parts, is set in the crossing state at least once of the interval between a first sidewall part 33 inner surface and a second sidewall part 34 inner surface in the deflected direction DD, and flow-rate measurement input is performed along the propagation route SW, to thereby enable flow-rate measurements, while a flow-rate distribution deliberately added is added in the flow direction. As a result, averaged flow measurement that accurately reflects the overall flow-velocity distribution becomes possible. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flow meter and a flow rate measuring line used therefor.

JP 2004-251653 A Japanese Patent No. 3528347

  Conventionally, an ultrasonic flowmeter for measuring a flow rate of city gas or water is known. In general, a “propagation time difference method” is used as a measurement principle at that time. This is provided with a pair of ultrasonic transmission / reception units upstream and downstream in the fluid flow direction of the flow path, alternately switching the ultrasonic transmission / reception direction between the ultrasonic transmission / reception units, and transmitted from the upstream ultrasonic transmission / reception unit. The time until the ultrasonic beam reaches the downstream ultrasonic transmission / reception unit (forward propagation time) and the time until the ultrasonic beam transmitted from the downstream ultrasonic transmission / reception unit reaches the upstream ultrasonic transmission / reception unit Time (reverse propagation time) is measured, and the average flow velocity and flow rate of the fluid flowing through the flow path are obtained from the time difference between the two (for example, Patent Document 1).

  By the way, in the ultrasonic flowmeter as described above, the flow in the flow rate measuring pipe has a unique three-dimensional distribution corresponding to the pipe shape. However, the conventional ultrasonic flowmeter has not been proposed with any measurement method considering the three-dimensional flow distribution in detail, and has a drawback that it easily causes measurement errors. For example, Patent Document 2 discloses a flow meter that measures only at the center portion of a pipe using a partition wall. However, there is a considerable amount of flow velocity change between laminar flow and turbulent flow between the low flow velocity region along the tube wall and the high flow velocity region in the center of the tube. It is obvious that becomes larger. Further, even if the flow rate measurement is performed separately in the tube wall region and the tube center region, the measurement of sweeping the flow velocity distribution in the cross section is not completed in each region, and it remains an error factor.

  An object of the present invention is to provide a flow meter capable of accurately measuring a flow velocity distribution in a pipe cross section and a flow rate measuring pipe used therefor.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the flowmeter of the present invention is:
The flow rate distribution in the axial cross section of the pipe is configured as a pipe having a fluid inlet and a fluid outlet, and the fluid to be measured is circulated from the fluid inlet to the fluid outlet in the pipe. A first flow velocity distribution deflector having a pipe shape whose peak position is offset from a pipe center line in a predetermined first direction in the axial cross section, and a flow peak position within the axial cross section from the pipe center line. And the second flow velocity distribution deflecting portion whose tube shape is determined so as to be biased in the second direction opposite to the first direction is arranged so that the first flow velocity distribution deflecting portion is located on the upstream side in the flow direction, The first flow velocity distribution deflection unit and the second flow velocity distribution deflection so that the flow rate measurement path traverses at least one time between the inner surface of the first side wall portion and the inner surface of the second side wall portion in the deflection direction by projection onto the pipe defining plane. Flow measurement pipes that are defined across ,
A flow rate measurement input means for performing a predetermined flow rate measurement input along the measurement path;
Flow rate response information detecting means for detecting flow rate response information for the flow rate measurement input;
It is characterized by having.

  The flow rate measuring line of the present invention is used in the flowmeter of the present invention and is configured as a line having a fluid inlet and a fluid outlet, and the fluid to be measured is fluidized from the fluid inlet in the pipe. In the flow velocity distribution in the axial cross section of the pipe when flowing toward the outlet, the pipe shape is determined so that the flow rate peak position is offset from the pipe center line in the first predetermined direction in the axial cross section. And a second flow velocity distribution deflecting portion whose pipe shape is determined such that a flow rate peak position is generated in a second direction opposite to the first direction in the axial cross section from the pipe center line. Are arranged so that the first flow velocity distribution deflection portion is located upstream in the flow direction, and the flow rate measurement path is projected onto the pipe defining plane and the first side wall inner surface and the second side wall inner surface in the deflection direction. The first flow velocity distribution bias Wherein the parts and defined across the second flow velocity distribution deflecting unit.

  The flow meter of the present invention is characterized by the fact that in the flow velocity distribution in the axial cross section of the pipe, the flow peak position is generated with a deviation from the pipe center line in a predetermined first direction in the axial cross section. A first flow velocity distribution deflecting portion having a defined shape, and a second flow velocity distribution having a pipe shape so that the flow rate peak position is offset from the pipe center line in a second direction opposite to the first direction in the axial section. It is in the point which provided the deflection | deviation part. When the fluid passes through the first flow velocity distribution deflection section and the second flow velocity distribution deflection section, the flow velocity distribution in the axial section is forcibly subjected to deflections in opposite directions. Changes can be brought about. Then, a flow rate measurement path that spans both flow velocity distribution deflection parts is set so as to cross between the inner surface of the first side wall part and the second side wall part in the deflection direction at least once, and the flow rate measurement is performed along the flow rate measurement path. By performing the input, it is possible to measure the flow rate while sweeping the artificially added flow velocity distribution in the flow direction. As a result, it is possible to measure an averaged flow that accurately reflects the total flow velocity distribution. For example, although there is a difference in the flow form between the area near the wall of the flow path and the central area (low flow → low flow Large, laminar flow → turbulent flow), correction, etc. are not required, and highly accurate and stable flow measurement is realized.

  The flow rate measurement input means can be an ultrasonic transmission means for transmitting a measurement ultrasonic wave to the fluid along the ultrasonic propagation path forming the measurement path, and the flow rate response information detection means is along the ultrasonic propagation path. The ultrasonic wave receiving means for receiving the measurement ultrasonic wave propagating as response information can be provided. Since the ultrasonic beam has high directivity and small loss due to waveform diffusion, it is possible to measure the flow rate with high accuracy, and it can be suitably used particularly for measuring the gas flow rate of city gas or LP gas. However, the flow rate measurement input means is not limited to the ultrasonic transmission / reception means, and can be applied to, for example, a hot wire flow meter. In this case, the heating wire stretched in the measurement path in contact with the fluid is the flow measurement input. Configure the means.

  When the pipe line for flow rate measurement is defined as the pipe center point at the bisection point of the entire length from the fluid inlet side end point to the fluid outlet side end point of the pipe center line, the overall shape of the pipe line is related to the pipe center point. It is good to set it to be point-symmetric. Thereby, the flow velocity distribution change along the flow direction becomes symmetric with respect to the pipe center point, and the reliability of the flow rate measurement obtained by averaging the flow velocity distribution in the channel axis cross section can be further increased.

  The first flow velocity distribution deflecting unit and the second flow velocity distribution deflecting unit have the curved bulging direction set to the second direction and the first direction, respectively, so that the flow velocity is larger on the curved inner peripheral side than on the curved outer peripheral side. The first and second curved pipe sections can be configured. By configuring the flow velocity distribution deflecting section as a curved pipe section, it is possible to smoothly deflect the flow velocity distribution by utilizing the fact that a flow velocity difference inevitably occurs between the curved outer peripheral side and the inner peripheral side based on the principle of continuity. it can.

  The first and second curved pipe sections can be two-dimensionally arranged along a predetermined pipe defining plane. That is, by setting the bending direction of all the curved pipe sections on the same plane (pipe definition plane), the layout of the flow rate measuring pipes is flattened, contributing to space saving. The flow rate measurement pipe line may be configured to include one first curved pipe line part and one second curved pipe line part, or may include a plurality of each. In either case, if the first curved pipe section and the second curved pipe section are configured to include the same number, the flow velocity distribution can be evenly deflected in each direction, and the reliability of the averaged flow measurement can be improved. It can be further increased. The first curved conduit portion and the second curved conduit portion occupy the arrangement end closest to the fluid inlet along the flow path by the first curved conduit portion, and the array end closest to the fluid outlet is the first end. It is good to arrange so that a double curved pipe part may occupy. If the configuration includes one each of the first curved pipeline portion and the second curved pipeline portion, the one located near the fluid inlet is located near the first curved pipeline portion and the fluid outlet. Is defined as the second curved duct section. On the other hand, in the case of including a plurality of first curved conduit portions and second curved conduit portions, the first curved conduit portions and the second curved conduit portions are alternately arranged in series along the flow path. Thus, the flow velocity distribution can be periodically deflected along the flow direction.

  In order to achieve the effect of bending deflection uniformly, it is desirable that the flow rate measuring conduit is configured so that the axial cross-sectional area is uniform in the flow direction. Further, the curved pipe member can be configured as an arcuate pipe member having the same radius of curvature of the pipe center line on the pipe defining plane. Such an arcuate tube member can uniformly produce the flow velocity distribution deflection effect in the flow channel direction in the curved tube member, and the flow of the entire flow rate measuring pipeline can be achieved by combining the arcuate tube members. The flow velocity distribution deflection specification along the direction can also be designed easily and freely.

  Further, the flow rate measurement pipe line can be configured to include at least one pair of first and second curved pipe line parts made of equivalent curved pipe members having a shape relationship that is mirror-inverted. Since the first curved pipe section and the second curved pipe section are equivalent curved pipe members that are mirror-inverted with each other, the two curved members can be configured as the same member with only the difference between the front and back sides. This contributes to simplification of design and design, and also improves the degree of freedom of design. In addition, the flow velocity distribution of the fluid flowing through the pipeline can be deflected more stably and accurately, and the symmetry along the flow direction of the flow velocity distribution change is further improved. Measurement reliability can be further increased.

  The other pipe member that couples the pair of the first bent pipe section and the second bent pipe section can be a straight pipe member. By inserting the straight pipe section as described above into the connection section between the first curved pipe section and the second curved pipe section, it becomes easy to secure the installation space for the ultrasonic transmission / reception section and increase the degree of freedom in design. Can do.

  Further, when the bisection point of the entire length from the fluid inlet side end point to the fluid outlet side end point of the pipe center line is determined as the pipe center point, the pipe center point has a shape relationship that is mirror-inverted with respect to each other. A pair of the curved conduit portion and the second curved conduit portion can be disposed in a positional relationship that is point-symmetric with each other. As a result, when considering the reference flow direction passing through the pipe center point on the pipe defining plane and orthogonal to the deflection direction, the symmetry of the flow velocity distribution with respect to the reference flow direction is further improved, The reliability of the flow rate measurement that averages the flow velocity distribution of can be further increased.

  In this case, the fluid inlet position when viewed from the pipeline center line is offset by a predetermined distance so as to move away from the pipeline center point in the deflection direction on the pipeline regulation plane, and also viewed from the pipeline center line. The fluid outlet position at this time can be configured to be offset at an equal distance in the direction opposite to the fluid inlet position in the deflection direction. By offsetting the fluid inlet position and fluid outlet position at the same distance from the pipe center point in the opposite direction, fine adjustment of the deflection characteristics of the flow velocity distribution according to the offset amount without losing the symmetry of the flow measurement pipe As a result, the flow rate measurement accuracy can be further optimized.

  In addition, an introduction conduit portion that guides the fluid flowing from the fluid inlet to the end of the first curved conduit portion while changing the direction toward the inflow end of the first curved conduit portion can be coupled to the end of the first curved conduit portion. . In addition, a lead-out conduit portion that guides the fluid while changing the direction of the fluid toward the fluid outlet can be coupled to the end of the second curved conduit portion on the fluid outlet side. Thereby, the freedom degree of attachment of the pipe for flow measurement to existing piping can be improved. The inflow direction of the fluid to the fluid inlet and the outflow direction from the fluid outlet should be determined in a direction perpendicular to the deflection direction on the pipe regulation plane. Space is advantageous.

  The axial cross section of the curved pipe section can be rectangular. In this case, the bending direction can be a long side of the rectangle. Curving in the direction of the long side of the rectangular axial cross section means that the pipe width becomes thinner than the pipe height, and it corresponds to the flow path where the installation space of the pipe width is limited. It becomes easy. In this case, by connecting to the front and rear pipes having a rectangular cross-section where the pipe width is thinner than the pipe height, for example, the flow velocity is symmetric with respect to each curved pipe portion without losing the symmetry of the S-shaped pipe line. Distribution can be secured. Furthermore, by increasing the aspect ratio of the axial section, the distribution of the fluid flowing in the pipe can be made closer to the two-dimensional flow from the three-dimensional flow, and the flow velocity distribution in the cross-sectional long side direction can be easily controlled uniformly. . Further, in the case of an S-shaped pipe formed symmetrically with respect to a point, when a reference flow direction passing through the pipe center point and orthogonal to the deflection direction on the pipe defining plane is considered, the flow velocity relating to the reference flow direction Distribution symmetry can be further improved.

  It is also possible to set the bending direction in the direction of the short side of the bending duct. Curving in the direction of the short side of the rectangular shaft section means a flat and wide flow path structure in which the pipe width is larger than the pipe height, and there are restrictions on the installation space in the pipe height direction. It becomes easy to correspond to the road. In addition, by increasing the aspect ratio of the axial section, the distribution of the fluid flowing in the pipe can be made closer to the two-dimensional flow from the three-dimensional flow, and the flow velocity distribution in the cross-section long side direction can be easily controlled uniformly. . Further, in the case of the S-shaped pipe formed symmetrically, the symmetry of the flow velocity distribution with respect to the reference flow direction can be further improved.

  Next, the flow rate measuring pipe of the present invention has an inlet-side main pipe connected to the fluid inlet and an outlet-side main pipe connected to the fluid outlet, and between the inlet-side main pipe and the outlet-side main pipe. , Branching from the inlet-side main pipe and integrated into the outlet-side main pipe, and a plurality of branch pipe sections each arranged in such a way that the first flow velocity distribution deflection section and the second flow velocity distribution deflection section are mixed in series. It is possible to have a structure inserted in By disassembling the flow into multiple branch pipes in parallel, the flow speed can be reduced by the branch pipe for large flow rates or high flow speeds, improving measurement accuracy and reducing power consumption for measurement. be able to. In this case, if the branch pipe cross-sectional area, the pipe length, and the pipe shape are determined to be equivalent to each other, the flow velocity can be reduced in a similar or close manner including the flow velocity distribution, and the measurement accuracy can be reduced. Contributes to further improvement.

An embodiment of a flow meter according to the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment in which the flow meter of the present invention is configured as an ultrasonic flow meter used as a general residential gas meter or the like. The ultrasonic flowmeter 1 is provided at a position different from each other in the flow direction of the fluid GF to be measured with respect to the flow passage forming portion 3 and the flow passage forming portion 3 that form the flow path of the fluid GF to be measured. While functioning so that the measurement ultrasonic wave is sent to the measurement fluid GF and the other is the measurement ultrasonic wave reception side, each of the measurement ultrasonic waves has directivity in a predetermined direction. A pair of ultrasonic transmission / reception units 2a and 2b capable of transmitting the ultrasonic beam SW is provided. The flow path forming unit 3 is made of metal, for example. The ultrasonic transmission transducer incorporated in each ultrasonic transmission / reception unit 2a, 2b is a flow path that obliquely penetrates the wall portion of the flow path forming unit 3 and the transducer mounting unit 2g integrated on the outer surface thereof. Are arranged in the vibrator arrangement hole 2h formed so as to communicate with each other. The ultrasonic beam emission surface of the transducer mounting portion 2g is between the inner peripheral surface of the transducer arrangement hole 2h and the extension surface of the inner surface of the flow path forming portion 3 toward the transducer arrangement hole 2h. Thus, a triangular fluid stagnation space 2d is formed.

  The flow path forming unit 3 constitutes a flow meter main body together with the ultrasonic transmission / reception units 2a and 2b, and the entire ultrasonic flow meter 1 is constituted by the flow meter main body and the control circuit unit 1E. The control circuit unit 1E includes a pair of ultrasonic transmission / reception units 2a and 2b. The upstream ultrasonic transmission / reception unit 2a located on the upstream side of the flow channel serves as the transmission side, and the downstream ultrasonic transmission / reception unit located on the downstream side of the flow channel. It has an ultrasonic drive mechanism 4 that is switchably driven between a first drive mode in which the 2b side is the receiving side and a second drive mode that is the opposite.

  A flow rate measurement gas (fluid) flows in the flow direction shown in the flow rate measurement flow path 3P of the ultrasonic flowmeter 1. In the flow path 3P, a downstream ultrasonic transmission / reception unit 2b is provided on the downstream side in the flow direction, and an upstream ultrasonic transmission / reception unit 2a is provided on the upstream side in the flow direction. These ultrasonic transmission / reception units 2a and 2b are ultrasonic transducers having an ultrasonic transducer such as a piezoelectric transducer, and have an ultrasonic transmission function for transmitting an ultrasonic beam by applying a drive voltage, It is combined with an ultrasonic wave reception function that outputs an electrical signal (reception signal) upon reception. The ultrasonic beam for measurement is sent out in a pulse shape having a predetermined wave number or less so as not to generate a standing wave between the ultrasonic transmission / reception units 2a and 2b in the flow path.

  The control circuit unit 1E is provided with the ultrasonic drive mechanism 4 and the peripheral circuit blocks 7 to 11 described above. The ultrasonic drive mechanism 4 includes a transmission unit 5, a reception unit 6, and a switching unit 4s. The transmission unit 5 is a circuit for inputting drive signals to the ultrasonic transmission / reception units 2a and 2b. The receiving unit 6 includes a switch or the like, and the drive mode is switched by switching the switch. The switching control of the receiving unit 6 is performed by the switching unit 4s. The amplifying unit 7 amplifies the ultrasonic wave received by the receiving unit 6 with a predetermined amplification factor, and inputs the amplified ultrasonic conversion signal to the mask time setting unit 8. The mask time setting unit 8 provides a minimum time during which the ultrasonic wave propagated through the flow path 3 does not reach after the ultrasonic wave is transmitted from the ultrasonic element 2a or 2b for noise countermeasures. Moreover, the zero cross point detection part 9 detects the zero cross point of the specific order wave (for example, 3rd wave) contained in the received ultrasonic waveform. The time measuring unit 10 includes a forward propagation time until the ultrasonic beam SW transmitted from the upstream ultrasonic transmission / reception unit 2a reaches the downstream ultrasonic transmission / reception unit 2b, and the second drive in the first drive mode. In this mode, the backward propagation time until the ultrasonic beam SW transmitted from the downstream ultrasonic transmission / reception unit 2b reaches the upstream ultrasonic transmission / reception unit 2a is measured. Moreover, the calculating part 11 calculates the average flow velocity and flow volume of the fluid which flow through the flow path 3P from the time difference between said forward propagation time and reverse propagation time.

  As shown in FIG. 2, the flow rate measuring line 3 is configured to have a three-dimensional shape unique to the present invention. That is, the flow rate measuring pipe 3 has a rectangular axial cross section and has a fluid inlet 31 and a fluid outlet 32 at each end in the pipe length direction. Then, as shown in FIG. 3, the pipe center line O is two-dimensionally bent by projection onto the virtual pipe defining plane DP with the first side K of the two adjacent sides of the rectangular axis cross section as a normal line. Has the shape. Specifically, when a direction parallel to the second side J of the two adjacent sides of the rectangular axis cross section on the pipe defining plane DP (in this embodiment, a rectangular short side) is defined as the deflection direction DD, the deflection direction A first curved conduit portion 36 and a second curved conduit portion 37 whose curved bulge directions are determined to be opposite to each other along DD are disposed adjacent to each other (the first one located upstream in the flow direction). A curved conduit portion 36).

  As shown in FIG. 2, the first and second ultrasonic transmission / reception units 2a and 2b are respectively attached to the walls of the flow rate measurement line 3 at both ends of the ultrasonic wave propagation path SW. 3 is transmitted and received along the propagation path SW. The propagation path SW is projected to the pipe defining plane DP so as to cross between the inner surface of the first side wall part 33 and the inner surface of the second side wall part 34 in the deflection direction DD. 36 and the second curved conduit portion 37.

  The first curved conduit portion 36 and the second curved conduit portion 37 are coupled in a directly adjacent manner to form an S-shaped conduit portion. Specifically, as shown in FIG. 3, a pipe center line O (a pipe cross section whose normal is the tangent direction of each position of the pipe internal stream line is considered, and the geometric center of gravity of each pipe cross section is considered. When the bisection point of the entire length from the end point on the fluid inlet 31 side to the end point on the fluid outlet 32 side is determined as the pipe center point Z, the line obtained by connecting the positions is defined as the pipe center line O). The shape is determined so as to be point-symmetric with respect to the pipe center point Z. In the orthographic projection onto the pipe defining plane DP, the first curved pipe section 36 and the second curved pipe section 37 are in a positional relationship in which the tangent directions of the pipe center line O on the connection end side coincide with each other. Has been placed. The curved inner surface shape of each curved pipe section 36, 37 is a cylindrical surface. In other words, each of the curved pipe sections 36 and 37 is configured as an arcuate pipe member having the same radius of curvature of the pipe center line on the pipe defining plane.

  Moreover, the 1st curved pipe part 36 and the 2nd curved pipe part 37 comprise the equivalent curved pipe part in the solid | 3D shape relationship which mutually mirror-inverted. Both pipe sections can be inseparably connected by welding or the like, and as shown in FIGS. 4 and 5, they are formed as individual curved pipe members having a mirror reversal relationship, which are mechanical fastening means. Can be combined and integrated. 4 and 5, coupling flanges 36 f and 37 f are formed at the connection ends of the first curved conduit portion 36 and the second curved conduit portion 37, and bolted via packing (not shown). ing.

  In addition, an introduction pipe section 38 that guides the fluid flowing in from the fluid inlet 31 to the end of the first curved pipe section 36 while changing the direction toward the inflow end of the first curved pipe section 36 is provided at the end of the first curved pipe section 36 on the fluid inlet side. It is integrally formed. In addition, a lead-out conduit portion 39 that guides the fluid flowing out from the outflow end while changing the direction toward the fluid outlet 32 is integrally formed at the end of the second curved conduit portion 37 on the fluid outlet side. The inflow direction of the fluid to the fluid inlet 31 and the outflow direction from the fluid outlet 32 are determined in a direction (hereinafter referred to as a reference flow direction X) orthogonal to the deflection direction DD on the pipe defining plane DP.

  Both the fluid inlet 31 formed in the inlet pipe section 38 and the fluid outlet 32 formed in the outlet pipe section 39 have a rectangular opening cross section, and a pipe having a rectangular axial section is connected. Is done. However, as shown in FIG. 7, the axial cross-sectional shapes of the introduction pipe line portion 38 and the lead-out pipe line portion 39 are configured to have a circular axial cross-sectional shape that can be connected to a general existing pipe, and the rectangular axial cross-section shape. Are formed separately from the first curved conduit portion 36 and the second curved conduit portion 37, and are fastened to the first curved conduit portion 36 and the second curved conduit portion 37 (here, flanges). It is also possible to adopt a configuration of combining them.

  The flow rate measuring pipe 3 is configured to have a uniform axial cross-sectional area in the flow direction. Each bending direction (deflection direction DD) of the 1st bending duct part 36 and the 2nd bending duct part 37 is set to the short side J direction of a rectangular-axis cross section. By increasing the aspect ratio of the cross section while curving in the short side J direction of the rectangular cross section, the distribution of the fluid flowing in the pipe can be made closer to the two dimensional flow, and the flow velocity in the long side K direction of the cross section It becomes easy to control the distribution uniformly.

  As shown in FIG. 2, the ultrasonic transmission / reception units 2 a and 2 b with respect to the flow rate measuring line 3 are on the first side K side of the rectangular axis cross section of the flow rate measuring line 3, that is, the first curved line 36. And the 1st ultrasonic transmission / reception part 2a is attached to one side of the main opposing wall parts 33 and 34 which form the curved surface side which concerns on the 2nd bending duct part 37, and the 2nd ultrasonic transmission / reception part 2b is attached to the other. Specifically, among the main opposing wall portions 33 and 34, those located on the curved outer peripheral side at the apex portion of the first curved conduit portion 36 are the first main wall portion 33 and the second curved conduit portion 37. The first ultrasonic transmission / reception unit 2 a is located on the curved outer peripheral side at the apex portion as the second main wall portion 34, and the first ultrasonic transmission / reception unit 2 a is more than the apex portion of the first curved duct portion 36 with respect to the first main wall portion 33. It is attached upstream in the fluid flow direction. In addition, the second ultrasonic transmission / reception unit 2 b is attached to the second main wall 34 on the downstream side in the fluid flow direction with respect to the apex of the second curved conduit 37.

  As shown in FIG. 5, each ultrasonic transmission / reception part 2a, 2b is the width direction of each main opposing wall part 33, 34 (the 1st side direction of the flow-measurement pipe line 3: the direction of the long side K of a rectangular-axis cross section). It is attached to the center of the. That is, the ultrasonic transmission / reception units 2 a and 2 b are attached at the same position in the first side direction of the flow rate measuring pipe 3. In addition, as shown in FIG. 2, the direction of ultrasonic transmission / reception is substantially parallel to the streamline tangential direction at each curved vertex of the first curved conduit portion 36 and the second curved conduit portion 37. In FIG. 3, the propagation path SW is the inner surface of the second main wall portion 33 between the curved vertex portions 36 p and 37 p of the first curved conduit portion 36 and the second curved conduit portion 37 in the reference flow direction X. The first reflection point 36r and the first reflection point 37r on the inner surface of the first main wall 34 are each reflected once. Accordingly, a non-reflection propagation path is formed between the first reflection point 36r and the second reflection point 37r.

  As shown in FIG. 3, if the curved bulging direction of the first curved conduit portion 36 is defined as the first side of the deflection direction DD and the curved bulging direction of the second curved conduit portion 37 is defined as the second side, Deflection direction DD When the fluid to be measured is circulated from the fluid inlet 31 toward the fluid outlet 32, the flow velocity distribution in the axial cross section of the pipe is the flow peak position in the first curved pipe section 36 in the deflection direction DD. In the second curved pipe section 37, the flow rate peak position is also biased to the first side.

  In other words, the first curved conduit portion 36 and the second curved conduit portion 37 have opposite curved bulging directions, so that the flow velocity distribution in the axial cross section is deflected in the opposite directions when the fluid passes. Forcibly, the flow velocity distribution changes artificially and stably along the flow direction. That is, the deflection direction DD (flow path height direction: rectangular axis) at each cross-sectional position (ξ1 to ξ9) along the flow direction of the fluid passing from the first curved conduit portion 36 to the second curved conduit portion 37. The flow velocity distribution in the direction of the short side J of the cross section changes continuously as shown in the figure.

  Since ultrasonic waves for measurement pass through such a channel while changing the passing position in the deflection direction DD for each cross section, the flow rate measurement is performed while sweeping the distribution continuously changing in the flow direction and averaging the sweeping distribution. Is made. For example, in the non-reflective direct connection section, the flow velocity distribution biased in the opposite direction of each curved member is swept and measured in half in the flow direction, and as a result, measurement that sweeps the entire flow velocity distribution is possible, and the total flow velocity distribution is accurately reflected The averaged flow can be measured, for example, even though there is a difference in the flow configuration between the wall vicinity and the center of the flow path (low flow → high flow, laminar flow → turbulent flow). Etc. is not required, and highly accurate and stable flow rate measurement is realized. In addition, the one curved pipe section 36 and the second curved pipe section 37 form an S-shaped pipe section that is point-symmetric with respect to the pipe center point Z, so that the flow velocity distribution in each curved pipe section is deflected. The state can be brought close to a symmetric relationship, and the measurement accuracy for the entire distribution of the biased flow is improved.

  In FIG. 3, in the vicinity of each reflection point R, Q (36r, 37r in FIG. 2) of the non-reflection direct connection section QR, the flow loss due to the wall friction is compensated by the flow deflection due to the curve, and the measurement is performed using the flow path that does not receive the deflection. Compared with the flow velocity distribution (close to the distribution of the cross section ξ5) in this case, the measurement loss at both shoulders corresponding to the vicinity of the wall surface is suppressed, and correction or the like for the loss can be unnecessary or reduced. Further, in the section on the upstream side of each reflection point R, half of the flow velocity distribution in the short side J direction on the inner surface side of the first main wall portion 33 is the same, and in the section on the downstream side of the reflection point Q, the same. Half of the inner surface side of the two main wall portions 34 is swept, but the flow velocity distribution is deflected toward the inner surface side of the corresponding wall portion in each section, thus contributing to the compensation of the flow loss due to the wall friction.

  As shown in FIG. 6, between the first curved pipeline portion 36 and the second curved pipeline portion 37 that are arranged so that the tangential directions of the pipeline center line O on the connection end side coincide with each other, It is also possible to arrange the straight pipe portion 40 along the tangential direction. By inserting the straight pipe section 40 as described above into the connection section between the first curved pipe section 36 and the second curved pipe section 37, the ultrasonic propagation section having a symmetric flow velocity distribution is increased, and the measurement accuracy is increased. Can be increased. Moreover, the insertion space of the straight pipe portion 40 makes it easy to secure the installation space for the ultrasonic transmission / reception portions 2a and 2b, and the degree of design freedom can be increased. In FIG. 6, an ultrasonic wave propagation path serving as a non-reflection direct connection section is formed in the straight pipe portion 40 while being reflected once by the inner surface of each curved pipe portion 36, 37 before and after the straight pipe portion 40. As shown, the first ultrasonic transmission / reception unit 2a is attached to the upstream end side of the straight pipe portion 40, and the second ultrasonic transmission / reception unit 2b is attached to the downstream end side. The direction of the ultrasonic propagation path can be made closer to the streamline direction in the straight pipe section 40, and the transmission / reception efficiency of the in-phase ultrasonic signal propagating in substantially the same direction as the flow velocity vector is increased, thereby improving the flow measurement accuracy. be able to.

  Next, as shown in FIG. 8, in the flow rate measuring pipe 3, the second side forming the deflection direction DD (curved bulging direction) of the rectangular axial section can be set to the long side K of the rectangle. is there. When the normal direction of the pipe defining plane DP is defined as the pipe width direction and the deflection direction DD is defined as the pipe height direction, the flow path cross section is rectangular and the long side K of the rectangular cross section is curved in the long side K direction. This means that the channel width is thinner than the channel height, and it is easy to deal with channels with restrictions on the installation space of the channel width. By increasing the aspect ratio of the cross section while curving in the long side K direction of the rectangular cross section, the distribution of the fluid flowing in the pipe can be made closer to the two dimensional flow, and the flow velocity in the long side K direction of the cross section It becomes easy to control the distribution uniformly. In addition, since the total flow velocity distribution can be captured simply by performing measurements in a non-reflective straight section where the ultrasonic propagation distance is relatively short, the drive voltage of the ultrasonic transducer and the amplification gain of the ultrasonic reception signal can be reduced. This makes it possible to save power.

  In FIG. 8, the attachment positions and the attachment angles in the reference flow direction X of the ultrasonic transmission / reception units 2a and 2b are set so that the propagation path SW is only in the non-reflection direct connection section, that is, reflection on the inner surface of the wall portion occurs. It is determined not to. The ultrasonic wave passing position of each axial section is swept in the long side K direction between the inner surface of the first side wall 33 and the inner surface of the second side wall 34 in the passing position deflection direction DD. As shown in FIG. 9, the first curved pipe section 36 and the second curved pipe section 37 are formed as individual curved pipe members having a mirror reversal relationship, and these are joined together by mechanical fastening means. (Here, as in FIG. 4 and FIG. 5, coupling flanges 36f and 37f are formed at the connection ends of the first curved conduit portion 36 and the second curved conduit portion 37, respectively. It has a structure that is bolted through a non-packing).

  Further, as shown in FIG. 10, a straight pipe member 40 similar to that in FIG. 6 includes a first curved pipe section 36 and a first curved pipe section 36 arranged so that the tangent directions of the pipe center line O on the connection terminal side coincide with each other. It is possible to arrange | position along the said tangent direction between the two curved pipe line parts 37. FIG. The attachment positions of the ultrasonic transmission / reception units 2a and 2b in the reference flow direction X are set between the curved apex portions 36p and 37p of the first curved conduit portion 36 and the second curved conduit portion 37, and the propagation path SW. Is configured to have only a non-reflection direct connection section.

  Next, FIGS. 11 to 15 show an example of a flow rate measuring pipe having a circular axial cross section (the positions of the ultrasonic wave propagation path SW and the ultrasonic wave transmitting / receiving units 2a and 2b are also shown as an example. But is not limited to this). In the flow rate measurement pipe 3, the first curved pipe section 36 and the second curved pipe section 37 are each formed in a semicircular arc shape and are directly connected at the pipe center point Z. A straight pipe part 140 arranged in the deflection direction is connected to the end of the first curved pipe part 36 on the fluid inlet side, and further, a quadrant arc-shaped direction changing pipe part 136 and an inlet straight pipe part. An introduction pipe line portion 38 made of 138 is connected. In addition, a straight pipe portion 140 arranged in the deflection direction is connected to the end of the second curved pipe portion 37 on the fluid outlet side, and further, a quadrant arc-shaped direction changing pipe portion 136 and a straight outlet portion are provided. A lead-out conduit section 39 including a pipe section 139 is connected.

  The flow rate measuring pipe 3 in FIG. 11 has a predetermined distance so that the position of the fluid inlet 31 when viewed from the pipe center line O is away from the pipe center point Z in the deflection direction DD on the pipe defining plane DP. Similarly, the position of the fluid outlet 32 when viewed from the pipe center line O is offset by the same distance δ in the deflection direction DD in the direction opposite to the position of the fluid inlet 31. By offsetting the fluid inlet 31 and the fluid outlet 32 at equal distances from the pipe center point Z in the opposite direction, the deflection characteristic of the flow velocity distribution can be adjusted according to the offset amount δ without losing the symmetry of the flow rate measuring pipe 3. Can be finely adjusted, and as a result, the flow measurement accuracy can be further optimized. As shown in FIG. 12, the offset amount δ is in the deflection direction connected to the fluid inlet side end of the first curved conduit portion 36 and the fluid outlet side end of the second curved conduit portion 37, respectively. Adjustment is possible according to the length of the straight pipe portions 140 and 140.

  In FIG. 13, the straight pipe portions 140 and 140 are omitted, and the inlet side ends of the first curved pipe section 36 and the direction changing pipe section 136, the second curved pipe section 37 and the direction changing pipe. This is an example in which the offset amount δ is set to zero by partially cutting out the outlet side ends of the path portion 137.

  On the other hand, FIG. 14 shows an example in which a straight pipe part 40 is additionally arranged between the first curved pipe part 36 and the second curved pipe part 37. Due to the arrangement of the straight pipe portion 40, the pipe center point Z moves to the inside of the straight pipe portion 40. The amount of offset δ in the deflection direction of the fluid inlet 31 and the fluid outlet 32 with respect to the pipe center point Z is the fluid inlet side end of the first curved pipe section 36 and the fluid outlet side of the second curved pipe section 37. Each length of the straight pipe sections 140 and 140 connected to the ends is L, and the length of the straight pipe section 40 between the first curved pipe section 36 and the second curved pipe section 37 is L0. Is determined by L- (1/2) L0. Further, in this embodiment, L = L0 is set, and the center position of the axial cross section corresponding to the curved apex of the fluid inlet 31 and the second curved pipe section 37 when viewed from the pipe center line O, The fluid outlet 32 and the central position of the axial cross section corresponding to the curved vertex of the first curved pipeline section 36 when viewed along the pipeline center line O are equal to each other.

  11, 12 and 14, the fluid inlet 31 is offset to the second side in the deflection direction DD and the fluid outlet 32 is offset to the first side in the deflection direction DD. However, as shown in FIG. It is also possible to offset in reverse.

  Next, in FIG. 6, the first curved pipe section 36, the straight pipe section 40, and the second curved pipe section 37 are configured as three independent pipe parts and are integrally coupled by fastening. As shown in FIG. 15, it is also possible to configure these as an inseparable S-shaped tube block 130. In such an S-shaped tube block 130, fastening connection is required only at the connection portion with the front and rear piping portions 21 and 22, and the assembly process can be simplified. In FIG. 15, the axial cross-sectional shape of the S-shaped tube block 130 is rectangular, but as shown in FIG. 16, it is also possible to form an S-shaped tube block 130 having an elliptical (or circular) axial cross section. Further, in addition to the first curved conduit portion 36 and the second curved conduit portion 37 being curved in an arc shape, it is also possible to adopt a pseudo-curved form that is bent in a polygonal line shape as shown in FIG. .

  Further, as shown in FIGS. 18 and 19, it is also possible to configure a flow rate measuring conduit 3 in which a plurality of first curved conduit portions 36 and second curved conduit portions 37 are connected in series ( The positions of the ultrasonic propagation path SW and the ultrasonic transmission / reception units 2a and 2b are also shown as an example, but are not limited thereto. 18 shows an example in which the axial cross-sectional shape is rectangular, and FIG. 19 shows an example in which the axial cross-sectional shape is circular. In any case, the first curved conduit portion 36 and the second curved conduit portion 37 have a semicircular arc shape, the first curved conduit portion 36 is positioned on the fluid inlet 31 side, and the second curved conduit portion 36 is on the fluid outlet 32 side. The curved conduit portions 37 are positioned, and the same number is alternately arranged.

  Moreover, in FIG. 18 and FIG. 19, although both the 1st curved pipeline part 36 and the 2nd curved pipeline part 37 were mutually connected directly, as shown in FIG. 20, it interposes another pipe member between them. You can also. In FIG. 20, a straight pipe part 140 in the deflection direction is interposed between a pair of the first curved pipe part 36 and the second curved pipe part 37 on the fluid inlet 31 side. In addition, a pair of the first curved pipeline portion 36 and the second curved pipeline portion 37 on the fluid inlet 31 side and a pair of the first curved pipeline portion 36 and the second curved pipeline portion 37 on the fluid outlet 32 side are. The three straight pipe portions are connected via a pipe assembly 140 'connected in a bowl shape while changing the direction.

  Next, as shown in FIGS. 21 to 24, the flow rate measuring pipe 3 has an inlet-side main pipe 238 connected to the fluid inlet 31 and an outlet-side main pipe 239 connected to the fluid outlet 32. Between the side main pipe line 238 and the outlet side main pipe line 239, it is branched from the inlet side main pipe line 238 and integrated into the outlet side main pipe line 239, and each of the first curved pipe line parts (first flow velocity distribution deflecting part). 36 and the second curved pipe section (second flow velocity distribution deflecting section) 37 may be structured such that a plurality of branch pipe sections 201 arranged in series are inserted in parallel. Since the total flow rate in the main pipelines 238 and 239 is decomposed into partial flows of a plurality of branch pipeline portions 201, the flow velocity is reduced in each branch pipeline portion 201 even in a high flow rate or high flow rate pipe. Etc. are less likely to occur, and the measurement accuracy can be improved. In some cases, power consumption required for measurement can be reduced (for example, ultrasonic output).

  In FIG. 21, the total number of branch pipe sections 201 is 2, and the pipe axis cross-sectional area, pipe length, and pipe shape are determined to be equivalent to each other. Specifically, each branch pipe portion 201 has a pipe width that is ½ of the pipe width of the main pipe lines 238 and 239, and the pipe height is equal to the main pipe lines 238 and 239. Each branch duct section 201 includes a pair of semicircular arc-shaped first curved duct section 36 and second curved duct section 37, and in a direction orthogonal to the bending direction (deflection direction). They are arranged in parallel (note that the two branch pipe sections 201 have their curvature phases reversed from each other). FIG. 23 shows a connecting bent portion 236 having a shape that is more angular than the curved conduit portions 36, 37 before and after the pair of the first curved conduit portion 36 and the second curved conduit portion 37 of each branch conduit portion 201. , 237 are arranged.

  On the other hand, in FIG. 22, each branch pipe section 201 has the same pipe width and pipe height as the main pipe lines 238 and 239, and the first curved pipe section (first flow velocity distribution deflecting section) 36 and A pair of second curved pipe sections (second flow velocity distribution deflecting sections) 37 are included and arranged in parallel in the bending direction (deflection direction) (note that the two branch pipe sections 201 are in a phase of curvature). Are in phase with each other). FIG. 24 shows an example in which three sets of similar branch pipe sections 201 are provided.

  In the flow rate measuring pipe of the present invention, the flow velocity distribution deflecting section is not limited to the curved pipe section. For example, in the example shown in FIG. 25, the inside of the integral box 430 having the fluid inlet 31 and the fluid outlet 32 is partitioned in a meandering manner by the flow partition walls 431 and 432, so that the first flow velocity distribution deflection unit and the second flow velocity A first bent flow passage 436 and a second bent flow passage 437 functioning as a distribution deflection portion are formed.

  Further, the flow rate measurement input means is not limited to the ultrasonic transmission / reception means. For example, as shown in FIG. 26, it is also possible to use a heating wire 451 stretched in the measurement path in contact with the fluid. For example, as a simple method, when the heating wire 451 is driven at a constant current, the temperature of the heating wire 451, that is, the electrical resistance value changes as the flow rate increases or decreases, so the voltage across the heating wire 451 is monitored. The flow rate can be measured. As an advanced method, a flow rate analysis circuit including a Wheatstone bridge incorporating a heating wire 451 and an energization drive control circuit for the heating wire 451 is provided so that the bridge equilibrium is maintained even when the flow rate changes. A method for feedback control of the drive current of the heating wire 451 can be exemplified. Since the drive current has a unique relationship with the flow velocity, it can be extracted as a flow velocity signal. However, since the measurement principle itself is publicly known, further detailed explanation is omitted.

  FIG. 27 shows the S-shaped flow rate measuring pipe having a rectangular axial cross section that can be used in the present invention, where the left column has the same long side when the deflection direction is set in the short side direction of the rectangular cross section. The flow velocity distribution simulation result when the deflection direction is set in the direction is shown by two-dimensional mapping, and is displayed so that the concentration becomes higher as the flow velocity is higher. Both the left column and the right column show the simulation results under the condition that the lower the mapping result is, the larger the flow rate is. It can be seen that the large flow rate region shifts to the inside of the curve as the flow velocity increases.

The block diagram which shows the example of whole structure of the ultrasonic flowmeter which concerns on one Embodiment of this invention. The figure which shows the 1st example of the pipe line for flow measurement used for the flowmeter of this invention. FIG. 3 is a diagram for explaining the operation of the flow rate measurement pipe in FIG. 2. The side view which shows the components structural example of the flow-measurement pipe line of FIG. Similarly perspective view. The figure which shows the 2nd example of the pipe line for flow measurement used for the flowmeter of this invention. The figure which shows the 3rd example of the pipe for flow measurement used for the flowmeter of this invention. The figure which shows the 4th example of the pipe for flow measurement used for the flowmeter of this invention. The side view which shows the example of a component structure of the pipe for flow measurement of FIG. The figure which shows the 5th example of the pipe for flow measurement used for the flowmeter of this invention. The figure which shows the 6th example of the flow-measurement pipe line used for the flowmeter of this invention. The figure which shows the 7th example of the pipe for flow measurement used for the flowmeter of this invention. The figure which shows the 8th example of the conduit for flow measurement used for the flowmeter of this invention. The figure which shows the 9th example of the pipe line for flow measurement used for the flowmeter of this invention. The figure which shows the 10th example of the flow-measurement pipe line used for the flowmeter of this invention. The figure which shows the 11th example of the conduit for flow measurement used for the flowmeter of this invention. The figure which shows the 12th example of the conduit for flow measurement used for the flowmeter of this invention. The figure which shows the 13th example of the conduit for flow measurement used for the flowmeter of this invention. The figure which shows the 14th example of the conduit for flow measurement used for the flowmeter of this invention. The figure which shows the 15th example of the flow-measurement pipe line used for the flowmeter of this invention. The figure which shows the 16th example of the pipe for flow measurement used for the flowmeter of this invention. The figure which shows the 17th example of the conduit for flow measurement used for the flowmeter of this invention. The figure which shows the 18th example of the flow-measurement pipe line used for the flowmeter of this invention. The figure which shows the 19th example of the conduit for flow measurement used for the flowmeter of this invention. The figure which shows the 20th example of the flow-measurement pipe line used for the flowmeter of this invention. The schematic diagram of the thermal type flow meter which shows one Embodiment of this invention. The figure which shows the flow-velocity distribution simulation result of the pipe for flow measurement used for the flowmeter of this invention.

Explanation of symbols

1 Flowmeter GF Fluid to be measured 2a, 2b Ultrasonic transceiver (flow measurement input means)
2d Fluid stagnation space 3 Pipe for measuring flow rate 3P Flow path 3W Waveguide space 4 Ultrasonic drive mechanism 31 Fluid inlet 32 Fluid outlet 33, 34 Main opposing wall 36 First curved pipe (first flow velocity distribution deflector)
37 Second curved pipe section (second flow velocity distribution deflecting section)
40 Straight pipe section 201 Branch pipe section 451 Heating wire (flow rate measurement input means)
O Pipe center line DP Pipe regulation plane DD Deflection direction

Claims (20)

In the flow velocity distribution in the axial cross section of the pipe when the fluid to be measured is circulated from the fluid inlet toward the fluid outlet in the pipe, the pipe is configured as a pipe having a fluid inlet and a fluid outlet. A first flow velocity distribution deflecting portion having a pipe shape determined so that a flow rate peak position is offset from a pipe center line in a predetermined first direction in the axial cross section; and the flow peak position is the pipe center line The first flow velocity distribution deflecting portion is located upstream of the second flow velocity distribution deflecting portion whose tube shape is determined so as to be biased in the second direction opposite to the first direction in the axial cross section. And the first flow rate measurement path crosses at least once between the inner surface of the first side wall portion and the inner surface of the second side wall portion in the deflection direction by projection onto the pipe defining plane. Flow velocity distribution deflector and second flow velocity distribution A flow rate measuring conduit defined across the direction unit,
A flow rate measurement input means for performing a predetermined flow rate measurement input along the measurement path,
Flow rate response information detecting means for detecting flow rate response information for the flow rate measurement input;
A flow meter characterized by comprising: The flow rate measurement input means is an ultrasonic transmission means for transmitting ultrasonic waves for measurement to the fluid along an ultrasonic wave propagation path forming the measurement path,
The flowmeter according to claim 1, wherein the flow rate response information detection unit includes an ultrasonic wave reception unit that receives the measurement ultrasonic wave propagating along the ultrasonic wave propagation path as the response information.   It is used for the flowmeter according to claim 1 or 2, and is configured as a pipe line having a fluid inlet and a fluid outlet, and the fluid to be measured flows from the fluid inlet to the fluid outlet in the pipe. In the flow velocity distribution in the axial cross section of the pipe line when the pipe shape is formed, the first pipe shape is determined so that the flow peak position is offset from the pipe center line in a predetermined first direction in the axial cross section. A flow velocity distribution deflecting section, and a second flow velocity distribution deflecting section whose tube shape is determined so that the flow rate peak position is generated in a second direction opposite to the first direction in the axial section from the pipe center line. Is arranged such that the first flow velocity distribution deflecting unit is located on the upstream side in the flow direction, and the flow rate measuring path is projected onto the pipe defining plane and the inner surface of the first side wall part and the second in the deflecting direction. Cross at least once between the inside of the side wall Flow rate measuring conduit, characterized in that a defined across said first flow velocity distribution deflecting portion and the second flow velocity distribution deflection unit as.   When the bisection point of the full length from the fluid inlet side end point of the pipe center line to the fluid outlet side end point is determined as the pipe center point, the entire shape of the pipe line is point-symmetric with respect to the pipe center point. The flow rate measuring conduit according to claim 3, which is defined as follows.   The first flow velocity distribution deflection unit and the second flow velocity distribution deflection unit have a curved bulging direction in the second direction and the first direction so that the flow velocity is larger on the curved inner circumferential side than on the curved outer circumferential side. The flow rate measuring conduit according to claim 3 or 4, comprising first and second curved conduit portions set in a direction.   6. The flow rate measuring pipe according to claim 5, wherein the first and second curved pipe sections are two-dimensionally arranged along a predetermined pipe defining plane.   The first curved conduit portion and the second curved conduit portion include the same number, and the first curved conduit portion and the second curved conduit portion are closest to the fluid inlet along the flow path. The flow rate measuring device according to claim 5 or 6, wherein the first curved pipe line portion occupies an array end, and the second curved pipe section occupies an array end closest to the fluid outlet. Pipeline.   A plurality of the first curved pipeline sections and the second curved pipeline sections are included, and the first curved pipeline sections and the second curved pipeline sections are alternately arranged in series along the flow path. The flow rate measuring conduit according to claim 7.   The flow rate measuring pipe according to claim 8, wherein each of the curved pipe members has a uniform axial cross-sectional area in a pipe length direction.   10. The flow rate measuring pipe according to claim 9, wherein the curved pipe member is an arcuate pipe member having a radius of curvature of a pipe center line equal to each other on the pipe defining plane.   The flow rate according to any one of claims 7 to 10, comprising at least one pair of the first and second curved pipe sections made of equivalent curved pipe members that are mirror-reversed in shape relation with each other. Measuring pipeline.   12. The flow rate measuring pipe according to claim 11, wherein the pair of the first curved pipe section and the second curved pipe section forms an S-shaped pipe section joined directly or through another pipe member. Road.   13. The flow rate measuring conduit according to claim 12, wherein the other conduit member that couples the pair of the first curved conduit portion and the second curved conduit portion is a straight pipe member.   When a bisection point of the entire length from the fluid inlet side end point of the pipe center line to the fluid outlet side end point is determined as a pipe center point, the pipe center points are in a shape relationship that is mirror-inverted with respect to each other. 14. The flow rate measurement conduit according to claim 12, wherein the pair of the first curved conduit portion and the second curved conduit portion is disposed in a positional relationship that is point-symmetric with each other.   In the first direction on the path defining plane, the fluid inlet position when viewed from the pipe centerline is offset by a predetermined distance from the pipe center point, and also in the second direction, 15. The flow rate measuring pipe according to claim 14, wherein the fluid outlet position when viewed from a pipe center line is located at an equal distance offset from the fluid inlet position from the pipe center point. The fluid flowing in from the fluid inlet is guided to the inflow end side of the first curved conduit portion, which is disposed closest to the fluid inlet, while changing the direction toward the inflow end of the first curved conduit portion. The inlet line member is joined,
An outlet pipe member that guides the fluid flowing out from the outflow end to the fluid outlet while being redirected is coupled to an outflow end side of the second curved pipe section that is disposed closest to the fluid outlet. The flow rate measuring conduit according to any one of claims 7 to 15.   17. The flow rate measurement pipe according to claim 5, wherein an axial cross section of the curved pipe section is a rectangle, and a bending direction is a long side of the rectangle.   17. The flow rate measurement pipe according to claim 5, wherein an axial cross section of the curved pipe section is a rectangle, and a bending direction is a short side of the rectangle.   An inlet-side main pipeline connected to the fluid inlet and an outlet-side main pipeline connected to the fluid outlet, and branching from the inlet-side main pipeline between the inlet-side main pipeline and the outlet-side main pipeline A plurality of branch pipe sections, which are integrated in the outlet main pipe and are arranged in such a manner that the first flow velocity distribution deflection section and the second flow velocity distribution deflection section are mixed in series with each other, are inserted in parallel. 19. A flow rate measuring conduit according to any one of claims 1 to 18.   The flow measurement pipe according to claim 19, wherein the plurality of branch pipe sections have a pipe axis cross-sectional area, a pipe length, and a pipe shape that are determined to be equivalent to each other.