JP2016223909A - Ultrasonic flow meter and flow velocity distribution controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flow meter which is impervious to drift in an improved manner.SOLUTION: An ultrasonic flow meter includes: a first ultrasonic transducer 101 for allowing a first ultrasonic signal to enter a measurement pipe 1 through which fluid flows; a second ultrasonic transducer 102 arranged at a position capable of receiving the first ultrasonic signal and allowing a second ultrasonic signal to enter the measurement pipe 1; and a flow velocity distribution controller 50 which is connected to the measurement pipe 1, which can rotate around a central axis of the measurement pipe 1, and which includes a large resistance region and a small resistance region for applying relatively-large resistance and relatively-small resistance to the progress of the fluid in a cross section respectively.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fluid measurement technique, and more particularly to an ultrasonic flow meter and a flow velocity distribution controller.

  An ultrasonic flowmeter may be used to measure the flow rate of the fluid (see, for example, Patent Documents 1 and 2). The ultrasonic flowmeter includes ultrasonic transducers provided on the upstream side and the downstream side of the pipe, respectively. The ultrasonic flowmeter sends ultrasonic waves toward the fluid flowing in the pipe, and propagates the ultrasonic waves propagating from the upstream to the downstream direction, and the ultrasonic wave propagating times from the downstream to the upstream direction. The flow velocity or flow rate of the fluid flowing in the pipe is calculated based on the time difference between Patent Document 3 discloses a correlation method, a zero cross method, and the like as a calculation method of a flow velocity or a flow rate.

  If a drift occurs in the fluid flowing in the pipe, the flow rate of the fluid may not be accurately measured with the ultrasonic flow meter. On the other hand, a plurality of ultrasonic transducer groups are arranged in the pipe, and the flow rate of the fluid is calculated by eliminating the influence of the drift based on the average value of the flow velocity of the fluid obtained from each ultrasonic transducer group. A method has been proposed (see, for example, Patent Document 4).

JP 2014-182097 A JP 2013-178125 A Special table 2013-88322 gazette No. 03-007787

  An object of the present invention is to provide an ultrasonic flowmeter and a flow velocity distribution controller that are less susceptible to drift.

  According to the aspect of the present invention, (a) a first ultrasonic transducer that inputs a first ultrasonic signal to a measurement pipe section in which a fluid flows in a circular cross section, and (b) a first ultrasonic wave. A second ultrasonic transducer disposed at a position where the signal can be received and inputting the second ultrasonic signal to the measurement pipe section; and (c) a second ultrasonic signal passing through the pipe through the second ultrasonic transducer. Based on the first time until reaching the ultrasonic transducer and the second time until the second ultrasonic signal reaches the first ultrasonic transducer through the pipe, the fluid in the measurement pipe section And (d) a strong resistance that is connected to the measurement pipe section and is rotatable with respect to the central axis of the measurement pipe section and that provides a relatively strong resistance to the progress of the fluid in the cross section. Provides relatively weak resistance to the area and fluid progression It comprises a resistor region, and flow velocity distribution controller provided with the ultrasonic flow meter is provided. In the present disclosure, the cross-sectional shape is a circle, as long as there is at least a portion having a circular cross-sectional shape, and there may be a portion having another shape in addition to the portion having a circular cross-sectional shape.

  In the flow velocity distribution of the fluid that has reached the flow velocity distribution controller, the flow velocity distribution controller rotates in the above ultrasonic flowmeter so that the strong resistance region hits the high flow velocity portion and the weak resistance region hits the low flow velocity portion. May be.

  In the above ultrasonic flow meter, the flow velocity distribution controller may be provided with a plurality of openings through which fluid passes asymmetrically with respect to the rotation center.

  In the above ultrasonic flowmeter, the flow velocity distribution controller includes a cylindrical side wall, a cylindrical member having a central axis different from that of the measurement pipe unit, and a plate radially disposed from the outer periphery of the cylindrical member to the side wall. And a shaped member. The cylindrical member may be cylindrical or rectangular.

  In the above ultrasonic flowmeter, the flow velocity distribution controller may include a small mesh area where the opening area of each hole is small and a large mesh area where the opening area of each hole is large. The center of the small mesh area may be different from the central axis of the flow velocity distribution controller, and the large mesh area may surround the small mesh area.

  In the above ultrasonic flowmeter, a protrusion may be provided on the outer periphery of the measurement pipe section, and a step portion that contacts the protrusion of the measurement pipe section may be provided in the flow velocity distribution controller. The protrusion of the measurement pipe part may make a round around the outer circumference of the measurement pipe part, and the step part of the flow velocity distribution controller may make a round around the outer circumference of the flow velocity distribution controller.

  The ultrasonic flow meter may further include a gasket disposed between the outer periphery of the measurement pipe portion and the step portion of the flow velocity distribution controller. The gasket may be an O-ring.

  Further, according to the aspect of the present invention, the flow velocity distribution controller connected to the measurement pipe section of the ultrasonic flowmeter, which is rotatable with respect to the central axis of the measurement pipe section, the flow velocity distribution in the cross section There is provided a flow velocity distribution controller provided with a strong resistance region that provides a relatively strong resistance to the progress of the fluid flowing through the controller and a weak resistance region that provides a relatively weak resistance to the progress of the fluid.

  In the flow velocity distribution of the fluid that has reached the flow velocity distribution controller, the flow velocity distribution controller may be rotated so that the strong resistance region hits a portion where the flow velocity is fast and the weak resistance region hits a portion where the flow velocity is slow.

  The flow velocity distribution controller may be provided with a plurality of openings through which fluid passes asymmetrically with respect to the rotation center.

  The flow velocity distribution controller includes a cylindrical side wall part, a cylindrical member having a central axis different from that of the measurement pipe part, and a plate-like member arranged radially from the outer periphery of the cylindrical member to the side wall part. It may be. The cylindrical member may be cylindrical or rectangular.

  The flow velocity distribution controller may include a small mesh area where the opening area of each hole is small and a large mesh area where the opening area of each hole is large. The center of the small mesh area may be different from the central axis of the flow velocity distribution controller, and the large mesh area may surround the small mesh area.

  According to the present invention, it is possible to provide an ultrasonic flowmeter and a flow velocity distribution controller that are less susceptible to drift.

It is a typical top view of the ultrasonic flowmeter concerning a 1st embodiment of the present invention. It is typical sectional drawing of the ultrasonic flowmeter which concerns on the 1st Embodiment of this invention seen from the II-II direction of FIG. It is typical sectional drawing of the flow-velocity distribution controller which concerns on the 1st Embodiment of this invention seen from the III-III direction of FIG. It is a typical side view of the flow-velocity distribution controller which concerns on the 1st Embodiment of this invention seen from the advancing direction of the fluid. It is a typical sectional view of the ultrasonic flow meter concerning a 1st embodiment of the present invention. It is a typical sectional view of the ultrasonic flow meter concerning a 1st embodiment of the present invention. It is a typical sectional view of the ultrasonic flow meter concerning a 1st embodiment of the present invention. It is typical sectional drawing of the ultrasonic flowmeter which concerns on the reference example of this invention seen from the perpendicular | vertical direction with respect to the advancing direction of a fluid. It is typical sectional drawing of the ultrasonic flowmeter which concerns on the reference example of this invention seen from the advancing direction of the fluid. It is typical sectional drawing of the ultrasonic flowmeter which concerns on the reference example of this invention seen from the advancing direction of the fluid. It is typical sectional drawing of the ultrasonic flowmeter which concerns on the reference example of this invention seen from the advancing direction of the fluid. It is typical sectional drawing of the ultrasonic flowmeter which concerns on the reference example of this invention seen from the advancing direction of the fluid. It is typical sectional drawing of the upstream piping connected to the ultrasonic flowmeter which concerns on the 1st Embodiment of this invention seen from the advancing direction of the fluid. It is typical sectional drawing of the flow-velocity distribution controller which concerns on the 1st Embodiment of this invention seen from the advancing direction of the fluid. It is a typical sectional view of the flow velocity distribution controller concerning a 1st embodiment of the present invention. It is a typical sectional view of the ultrasonic flowmeter concerning a 2nd embodiment of the present invention. It is a typical sectional view of a flow velocity distribution controller concerning a 2nd embodiment of the present invention.

  Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(First embodiment)
The ultrasonic flowmeter according to the first embodiment is a top view of FIG. 1, FIG. 2 is a cross-sectional view seen from the II-II direction, and a cross-sectional view seen from the III-III direction of FIG. As shown in FIG. 3, the first ultrasonic transducer 101 that inputs the first ultrasonic signal to the measurement pipe section 1 having a circular cross section through which the fluid flows, and the first ultrasonic signal can be received. A second ultrasonic transducer 102 disposed at a position and receiving a second ultrasonic signal to the measurement piping unit 1, and the first ultrasonic signal passes through the measurement piping unit 1 and the second ultrasonic transducer. Based on the first time until reaching 102 and the second time until the second ultrasonic signal reaches the first ultrasonic transducer 101 through the measurement pipe 1, the measurement pipe A flow velocity calculation unit 302 that calculates the flow velocity of the fluid in 1 , Connected to the measurement piping unit 1, rotatable with respect to the central axis of the measurement piping unit 1, and in a cross section, a strong resistance region that gives a relatively strong resistance to the progress of fluid, and a relative to the progress of fluid A flow velocity distribution controller 50 provided with a weak resistance region that provides a weak resistance.

  As shown in FIG. 2, the flow velocity distribution controller 50 is connected to the upstream side of the measurement piping unit 1, for example. An upstream side of the flow velocity distribution controller 50 is connected to the upstream pipe 2 having a circular cross section. A flange-shaped protrusion 12 is provided at the end of the upstream pipe 2. The protrusion 12 circulates on the outer periphery of the upstream pipe 2. When viewed from the central axis direction of the measurement pipe portion 1, the outer peripheral shape of the protrusion 12 is a circle.

  At the upstream end of the flow velocity distribution controller 50, a step 52 </ b> A on the ridge that is in contact with the protrusion 12 of the upstream pipe 2 is provided. As shown in FIG. 4 as viewed from the direction in which the central axis of the flow velocity distribution controller 50 having a circular cross-sectional shape extends upstream, the stepped portion 52A circulates on the outer periphery of the flow velocity distribution controller 50. The inner and outer peripheral shapes of the stepped portion 52A are circles. For example, the diameter of the inner periphery of the step portion 52A of the flow velocity distribution controller 50 is equal to the diameter of the outer periphery of the protrusion portion 12 of the upstream pipe 2 shown in FIG. It is inserted into the step 52A of the container 50.

  In the fluid flow direction, the width of the inner periphery of the step 52A of the flow velocity distribution controller 50 is longer than the width of the outer periphery of the protrusion 12 of the upstream pipe 2. A gasket 4 such as an O-ring is disposed between the outer periphery of the upstream pipe 2, the inner periphery of the step portion 52 </ b> A of the flow velocity distribution controller 50, and the side wall of the protrusion 12 of the upstream pipe 2. Further, an annular member 6 is fixed to the outer periphery of the upstream pipe 2. The annular member 6 is fixed to the opposite side of the opening of the upstream pipe 2 with respect to the protrusion 12. The diameter of the inner periphery of the annular member 6 is equal to the diameter of the outer periphery of the upstream pipe 2, and the inner periphery of the annular member 6 is in close contact with the outer periphery of the upstream pipe 2. The height of the annular member 6 is higher than the height of the protrusion 12, and the side wall of the annular member 6 is in contact with the end surface of the step portion 52 </ b> A of the flow velocity distribution controller 50.

  On the downstream side of the flow velocity distribution controller 50, the measurement pipe section 1 having a circular cross section is connected. A flange-shaped projection 11 is provided at the end of the measurement pipe 1. The protrusion 11 circulates on the outer periphery of the measurement piping unit 1. When viewed from the central axis direction of the measurement pipe portion 1, the outer peripheral shape of the protrusion 11 is a circle.

  At the downstream end of the flow velocity distribution controller 50, a step portion 52 </ b> B on the ridge that is in contact with the protruding portion 11 of the measurement pipe portion 1 is provided. The stepped portion 52 </ b> B circulates on the outer periphery of the flow velocity distribution controller 50. When viewed from the direction in which the central axis of the flow velocity distribution controller 50 extends to the downstream side, the inner and outer peripheral shapes of the stepped portion 52B are circles. For example, the diameter of the inner periphery of the step 52B of the flow velocity distribution controller 50 is equal to the diameter of the outer periphery of the protrusion 11 of the measurement pipe portion 1, and the protrusion 11 at the end of the measurement pipe portion 1 is connected to the flow velocity distribution controller 50. Is inserted into the step 52B.

  In the fluid flow direction, the width of the inner periphery of the stepped portion 52 </ b> B of the flow velocity distribution controller 50 is longer than the width of the outer periphery of the protruding portion 11 of the measurement pipe portion 1. A gasket 5 such as an O-ring is disposed between the outer periphery of the measurement piping unit 1, the inner periphery of the stepped portion 52 </ b> B of the flow velocity distribution controller 50, and the side wall of the projection 11 of the measurement piping unit 1. Further, an annular member 7 is fixed to the outer periphery of the measurement piping unit 1. The annular member 7 is fixed to the protrusion 11 on the opposite side of the opening of the measurement pipe portion 1. The diameter of the inner periphery of the annular member 7 is equal to the diameter of the outer periphery of the measurement pipe part 1, and the inner periphery of the annular member 7 is in close contact with the outer periphery of the measurement pipe part 1. The height of the annular member 7 is higher than the height of the protrusion 11, and the side wall of the annular member 7 is in contact with the end surface of the stepped portion 52 </ b> B of the flow velocity distribution controller 50.

  As shown in FIGS. 2 and 3, the cross section of the flow velocity distribution controller 50 is provided with a plurality of openings 51 a to 51 g through which fluid passes asymmetrically with respect to the rotation axis. The rotation axis of the flow velocity distribution controller 50 coincides with an axis obtained by extending the central axis of the measurement piping unit 1 in the upstream direction.

  The flow velocity distribution controller 50 is, for example, a cylindrical tubular member having a cylindrical side wall portion 53 and a central axis that is disposed in the cylindrical side wall portion 53 and that is different from the central axis of the measurement pipe portion 1. 54, and plate-like members 55 a to 55 e arranged radially from the outer periphery of the cylindrical member 54 to the side wall portion 53. For example, the central axis of the cylindrical side wall part 53 coincides with the central axis of the measurement pipe part 1. A hollow portion of the cylindrical side wall portion 53 forms an opening 51a. Each of the plate-like members 55 a to 55 e is connected to the side wall portion 53 and the cylindrical member 54. The cylindrical member 54 is held in the cylindrical side wall 53 by the plate-like members 55a to 55e.

  A space surrounded by the plate-like members 55a and 55b, the cylindrical member 54, and the side wall 53 forms an opening 51b. A space surrounded by the plate-like members 55b and 55c, the cylindrical member 54, and the side wall portion 53 forms an opening 51c. A space surrounded by the plate-like members 55c and 55d, the cylindrical member 54, and the side wall portion 53 forms an opening 51d. A space surrounded by the plate-like members 55d and 55e, the cylindrical member 54, and the side wall 53 forms an opening 51e. A space surrounded by the plate-like members 55e and 55f, the cylindrical member 54, and the side wall 53 forms an opening 51f. A space surrounded by the plate-like members 55f and 55a, the cylindrical member 54, and the side wall 53 forms an opening 51g.

  The opening areas of the openings 51d, 51e, and 51f are larger than the opening areas of the openings 51g, 51b, and 51c. A region including the openings 51d, 51e, and 51f having a large opening area is a weak resistance region that gives weak resistance to the progress of the fluid, and a region including the openings 51g, 51b, and 51c having a small opening area is used for the progress of the fluid. This is a strong resistance region that gives a strong resistance. The weak resistance in the weak resistance region is a resistance relatively weak with respect to the resistance in the strong resistance region, and the strong resistance in the strong resistance region is a resistance relatively strong with respect to the resistance in the weak resistance region. It means that there is.

  With respect to the upstream pipe 2 and the measurement pipe section 1 that are fixed and cannot rotate as shown in FIG. 2, the flow velocity distribution controller 50 having a circular cross-sectional shape is rotatable with respect to the rotation axis that is the central axis. In the flow velocity distribution of the fluid that has reached the flow velocity distribution controller 50, the flow velocity distribution controller 50 is rotated so that a strong resistance region hits a portion where the flow velocity is fast and a weak resistance region hits a portion where the flow velocity is slow. The flow velocity distribution controller 50 can be manually rotated continuously, for example, but may be rotated by a rotating machine such as a motor.

  The first ultrasonic transducer 101 is disposed on the upstream side of the fluid flowing in the measurement piping unit 1, and the second ultrasonic transducer 102 is disposed on the downstream side. As shown in FIG. 5, the first ultrasonic signal emitted from the first ultrasonic transducer 101 travels through the fluid in the measurement piping unit 1 and is received by the second ultrasonic transducer 102. Further, as shown in FIG. 6, the second ultrasonic signal emitted from the second ultrasonic transducer 102 travels through the fluid in the measurement piping unit 1 and is received by the first ultrasonic transducer 101. . For example, the first ultrasonic transducer 101 and the second ultrasonic transducer 102 are alternately applied with drive signals and alternately generate ultrasonic signals.

  The 1st ultrasonic signal emitted from the 1st ultrasonic transducer 101 crosses the central axis of the measurement piping part 1, for example. In addition, the second ultrasonic signal emitted from the second ultrasonic transducer 102 also crosses the central axis of the measurement piping unit 1.

  Inside the measurement piping unit 1, the fluid flows at a flow velocity v. As described above, the first ultrasonic transducer 101 is disposed on the upstream side of the fluid flowing in the measurement piping unit 1, and the second ultrasonic transducer 102 is disposed on the downstream side. Therefore, the first ultrasonic signal emitted from the first ultrasonic transducer 101 shown in FIG. 5 propagates through the cavity in the measurement piping unit 1 according to the flow of the fluid. On the other hand, the second ultrasonic signal emitted from the second ultrasonic transducer 102 shown in FIG. 6 propagates in the cavity in the measurement pipe part 1 against the fluid flow. Therefore, in the hollow part in the measurement piping part 1, a difference due to the flow velocity v of the fluid occurs between the propagation time of the first ultrasonic signal and the propagation time of the second ultrasonic signal.

When the angle of the traveling direction of the first ultrasonic signal with respect to the traveling direction of the fluid in the measurement piping unit 1 shown in FIG. 5 is θ, and the sound velocity of the ultrasonic wave in the fluid in the measuring piping unit 1 is c, the first super The propagation time t ₁ required for the sound wave signal to cross the hollow portion in the measurement piping unit ₁ is given by the following equation (1).
t ₁ = L / (c + v · cos θ) (1)
Further, the angle of the traveling direction of the second ultrasonic signal with respect to the traveling direction of the fluid in the measurement piping unit 1 shown in FIG. 6 is also θ, and the second ultrasonic signal crosses the cavity in the measuring piping unit 1. The propagation time t ₂ required for this is given by the following equation (2).
t ₂ = L / (cv · cos θ) (2)
Here, as shown in FIG. 7, L represents the length that each of the first ultrasonic signal and the second ultrasonic signal crosses the cavity in the measurement piping unit 1.

From the above equations (1) and (2), the sum of the reciprocal of the propagation time t _{1 and} the reciprocal of the propagation time t ₂ is given by the following equation (3).
1 / t ₁ + 1 / t ₂ = (c + v · cos θ) / L + (c−v · cos θ) / L
= 2c / L (3)
From the above equation (3), the speed of sound c in the fluid flowing through the cavity in the measurement pipe unit 1 is given by the following equation (4).
c = L (1 / t ₁ + 1 / t ₂ ) / 2 (4)

Further, from the above equations (1) and (2), the difference Δt between the propagation time t ₂ and the propagation time t ₁ is given by the following equation (5).
Δt = t ₂ −t ₁ ≈ (2 Lv · cos θ) / c ² (5)
From the above equation (5), the flow velocity v of the fluid flowing through the cavity in the measurement piping unit 1 is given by the following equation (6). However, the flow velocity v calculated by the following equation (6) is an average flow velocity of the fluid on the propagation paths of the first and second ultrasonic signals.
v = c ² Δt / (2L · cos θ) (6)
Here, the angle θ and the length L are known. The sound speed c can be calculated from the above equation (4). Therefore, by measuring the time difference Δt between the propagation times t ₁ and t ₂ of the first and second ultrasonic signals, it is possible to calculate the flow velocity v of the fluid flowing through the cavity in the measurement pipe unit 1.

The time difference Δt between the propagation times t ₁ and t ₂ of the first and second ultrasonic signals may be obtained by a correlation method. In this case, a cross-correlation function between the entire waveform of the received signal of the first ultrasonic signal and the entire waveform of the received signal of the second ultrasonic signal is obtained. The time difference Δt between the propagation times t ₁ and t ₂ of the second ultrasonic signal can be obtained.

Further, as shown in the following equation (7), the fluid flow rate Q can be calculated by multiplying the fluid flow velocity v by the cross-sectional area S of the measurement pipe section 1.
Q = S · v (7)

  The first ultrasonic transducer 101 and the second ultrasonic transducer 102 are electrically connected to a central processing unit (CPU) 300. The CPU 300 performs the first time from when the first ultrasonic signal is emitted from the first ultrasonic transducer 101 to the second ultrasonic transducer 102 through the measurement piping unit 1 and the second time. A time difference specifying unit 301 that measures a second time from when an ultrasonic signal is emitted from the second ultrasonic transducer 102 to when it reaches the first ultrasonic transducer 101 through the pipe; And a flow rate calculation unit 302 that calculates the flow rate of the fluid in the measurement pipe unit 1 based on the second time.

  The time difference specifying unit 301 monitors the timing at which the first ultrasonic transducer 101 emits the first ultrasonic signal and the timing at which the second ultrasonic transducer 102 receives the first ultrasonic signal, A first time from when the first ultrasonic signal is emitted from the first ultrasonic transducer 101 to when the first ultrasonic signal reaches the second ultrasonic transducer 102 through the measurement piping unit 1 is measured.

  Here, the timing at which the first ultrasonic transducer 101 is driven may be the timing at which the first ultrasonic signal is emitted from the first ultrasonic transducer 101. Further, when the intensity of the received signal of the second ultrasonic transducer 102 is small at the timing when the first ultrasonic signal reaches the second ultrasonic transducer 102, the timing at which the characteristic point in the waveform of the received signal is obtained. Therefore, the timing at which the first ultrasonic signal reaches the second ultrasonic transducer 102 may be calculated backward. The feature point of the reception signal is, for example, a point (zero cross point) at which the intensity of the reception signal after a predetermined number of maximum points in the amplitude waveform of the reception signal becomes zero.

  The time difference specifying unit 301 monitors the timing at which the second ultrasonic transducer 102 emits the second ultrasonic signal and the timing at which the first ultrasonic transducer 101 receives the second ultrasonic signal. Then, a second time from when the second ultrasonic signal is emitted from the second ultrasonic transducer 102 to when the second ultrasonic signal reaches the first ultrasonic transducer 101 through the measurement piping unit 1 is measured.

  Here, the timing at which the second ultrasonic transducer 102 is driven may be the timing at which the second ultrasonic signal is emitted from the second ultrasonic transducer 102. In addition, when the intensity of the reception signal of the first ultrasonic transducer 101 at the timing when the second ultrasonic signal reaches the first ultrasonic transducer 101 is small, a feature point (for example, a zero cross point in the waveform of the reception signal) The timing at which the second ultrasonic signal reaches the first ultrasonic transducer 101 may be calculated backward from the timing at which () is obtained.

  The time difference specifying unit 301 calculates a difference value between the second time and the first time, and transmits the calculated value to the flow velocity calculating unit 302. However, the time difference specifying unit 301 may directly measure the difference between the second time and the first time, or may obtain it by the correlation method as described above.

Based on the first and second propagation times t ₁ and t ₂ , the flow velocity calculation unit 302 calculates the sound velocity c in the fluid flowing through the cavity in the measurement pipe unit 1 from the above equation (4). Further, the flow velocity calculation unit 302 flows through the cavity in the measurement pipe unit 1 from the above equation (6) based on the difference Δt between the first and second propagation times t ₁ and t ₂ and the calculated sound velocity c. The flow velocity v of the fluid is calculated, and the flow rate Q of the fluid is calculated from the above equation (7).

  A measured value storage unit 352 and an output device 401 are connected to the CPU 300. The flow velocity calculation unit 302 stores the calculated flow velocity v and flow rate Q of the fluid in the measurement value storage unit 352 that is a storage device, and outputs it to the output device 401.

  Here, when there is no bias in the flow velocity distribution of the fluid that reaches the measurement piping section 1, as shown in FIG. 8, even if there is no flow velocity distribution controller, as shown in FIG. The flow velocity is the fastest on the axis, and the flow velocity becomes slower as it approaches the side wall of the measurement pipe section 1 symmetrically about the central axis. In this case, the propagation path of the first and second ultrasonic signals intersecting the central axis wherever the set of the first and second ultrasonic transducers 101 and 102 is located with respect to the central axis of the measurement piping unit 1. The average fluid flow velocity above is the same.

  On the other hand, for example, as shown in FIGS. 10, 11, and 12, when the flow velocity distribution of the fluid flowing in the measurement pipe unit 1 is not symmetric with respect to the central axis but is biased, Even if the average flow velocity of the fluid is the same in FIGS. 10 to 12, the average flow velocity of the fluid on the propagation path of the ultrasonic signal is different in FIGS. Specifically, in the flow velocity distribution of the fluid, if a large amount of the first and second ultrasonic signals propagate through the portion where the flow velocity is high, the measured average flow velocity becomes faster, and the portion where the flow velocity is slower becomes the first and second portions. If many ultrasonic signals of are propagated, the average flow velocity to be measured becomes slow.

  However, although the average flow velocity of the fluid in the cross section of the measurement piping unit 1 is the same, it is preferable that the measured average flow velocity varies depending on the arrangement of the first and second ultrasonic transducers 101 and 102. Absent.

  On the other hand, when the flow velocity of the fluid reaching the flow velocity distribution controller 50 from the upstream pipe 2 is distributed as shown in FIG. 13, as shown in FIG. Thus, the flow velocity distribution controller 50 is rotated so that the weak resistance region of the flow velocity distribution controller 50 is in the portion where the flow velocity is slow. Thereby, the influence of drift can be relieved. Normally, the inside of the pipe cannot be observed, but when the measured average flow velocity is the fastest, the flow velocity distribution controller 50 is most effectively arranged, and the influence of the flow velocity distribution is most suppressed. Therefore, the flow velocity distribution controller 50 may be rotated to control the flow velocity distribution in the measurement piping unit 1 so that the average flow velocity to be measured is the fastest.

  When measuring the flow rate of the fluid with the ultrasonic flowmeter according to the first embodiment, for example, first, a fluid with a constant flow rate is caused to flow through the measurement piping unit 1 for adjustment, and the flow velocity distribution controller 50 is set. While rotating, the rotation angle of the flow velocity distribution controller 50 that maximizes the measured flow velocity or flow rate is searched for. When the measured flow velocity or flow rate is maximized, the rotation of the flow velocity distribution controller 50 is stopped, and the flow of the adjustment fluid is stopped. Thereafter, the fluid to be measured is caused to flow through the flow velocity distribution controller 50 and the measurement piping unit 1 to measure the flow velocity or flow rate.

  Since the drift is affected by the shapes and paths of the pipes upstream and downstream of the ultrasonic flowmeter, the state of the drift may not change. In this case, once the rotation angle of the flow velocity distribution controller 50 that maximizes the measured flow velocity or flow rate is found, then the flow velocity or flow rate of the fluid to be measured may be measured while maintaining the same angle. However, when the state of drift changes, a fluid having a constant flow rate is flowed to the measurement piping unit 1 for adjustment, and the rotation speed of the flow velocity distribution controller 50 at which the measured flow velocity or flow rate becomes maximum is searched. , As appropriate.

  Conventionally, it has been proposed to fix a combination of a large number of ultrasonic transducers around a fixed tube and select a combination of ultrasonic transducers that maximizes the measured flow velocity or flow rate. However, if the state of drift does not change, the ultrasonic transducer that was not selected is not used and is wasted, and does not meet the manufacturing cost.

  On the other hand, in the ultrasonic flowmeter according to the first embodiment, since the flow velocity distribution controller 50 can be continuously rotated, a large number of ultrasonic transducers are not required and a pair of ultrasonic transducers is required. The effect of drift can be mitigated while the is fixed.

  The cylindrical member 54 is not limited to a cylindrical shape, and may be a rectangular tube shape such as a hexagonal tube shape as shown in FIG.

(Second Embodiment)
In the ultrasonic flowmeter according to the second embodiment, as shown in FIGS. 16 and 17, the flow velocity distribution controller 50 includes a small mesh region 151 having a small opening area of each hole and each hole's opening area. A large mesh area 152 having a large opening area. The small opening area in the small mesh region 151 is a relatively small opening area with respect to the opening area in the large mesh region 152, and the large opening area in the large mesh region 152 is the opening area in the small mesh region 151. It means that the opening area is relatively large.

  In the second embodiment, the small mesh area 151 is a strong resistance area that gives a strong resistance to the progress of fluid, and the large mesh area 152 is a weak resistance area that gives a weak resistance to the progress of fluid. is there.

  For example, the center of the small mesh area 151 may be different from the central axis that is the rotation axis of the flow velocity distribution controller 50, and the large mesh area 152 may surround the small mesh area 151. Also in the second embodiment, when the flow velocity distribution of the fluid reaching the flow velocity distribution controller 50 from the upstream pipe 2 is decentered, the small mesh region 151 of the flow velocity distribution controller 50 hits the portion where the flow velocity is fast, The flow velocity distribution controller 50 is rotated so that the large mesh region 152 of the flow velocity distribution controller 50 hits the portion where the flow velocity is low. Thereby, the influence of drift can be relieved.

(Other embodiments)
Although the present invention has been described by the embodiments as described above, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques should be apparent to those skilled in the art. For example, FIG. 2 shows an example in which the first and second ultrasonic transducers 101 and 102 are arranged to face each other. On the other hand, the first and second ultrasonic transducers 101 and 102 are arranged in parallel to the central axis direction of the measurement pipe unit 1, and the ultrasonic signals reflected in the measurement pipe unit 1 are converted into the first and first ultrasonic transducers. Each of the two ultrasonic transducers 101 and 102 may receive the signal. Further, the ultrasonic signal may be reflected a plurality of times inside the measurement piping unit 1.

Furthermore, the flow velocity v of the fluid flowing through the hollow portion in the measurement pipe unit 1 may be obtained by a reciprocal difference in propagation time given by the following equation (8).
v = (L / 2 cos θ) {(1 / t ₁ ) − (1 / t ₂ )} (8)
According to the inverse propagation time difference method, the flow velocity v of the fluid can be calculated even if the sound velocity c is unknown. Thus, it should be understood that the present invention includes various embodiments and the like not described herein.

DESCRIPTION OF SYMBOLS 1 Measurement piping part 2 Upstream piping 4, 5 Gasket 6, 7 Annular member 11, 12 Protrusion part 50 Flow velocity distribution controller 51a, 51b, 51c, 51d, 51e, 51f, 51g Opening 52A, 52B Step part 53 Side wall part 54 Cylinder 55a, 55b, 55c, 55d, 55e, 55f Plate member 101 First ultrasonic transducer 102 Second ultrasonic transducer 151 Small mesh region 152 Large mesh region 300 Central processing unit 301 Time difference specifying unit 302 Flow velocity calculation Unit 352 measured value storage unit 401 output device

Claims (20)

A first ultrasonic transducer that inputs a first ultrasonic signal to a measurement pipe section having a circular cross-sectional shape through which the fluid flows;
A second ultrasonic transducer that is disposed at a position capable of receiving the first ultrasonic signal and that enters the second ultrasonic signal to the measurement piping unit;
A first time until the first ultrasonic signal reaches the second ultrasonic transducer through the pipe, and the first ultrasonic wave passes through the pipe and the first ultrasonic wave. A flow rate calculation unit that calculates a flow rate of the fluid in the measurement pipe unit based on a second time until reaching the transducer;
A strong resistance region connected to the measurement pipe section and rotatable with respect to a central axis of the measurement pipe section, and giving a relatively strong resistance to the progress of the fluid in a cross section, and relative to the progress of the fluid A flow resistance distribution controller provided with a weak resistance region that gives weak resistance to
An ultrasonic flow meter comprising:   In the flow velocity distribution of the fluid that has reached the flow velocity distribution controller, the flow velocity distribution controller is rotated so that the strong resistance region hits a portion where the flow velocity is fast and the weak resistance region hits a portion where the flow velocity is slow. The ultrasonic flowmeter according to claim 1.   The ultrasonic flowmeter according to claim 1 or 2, wherein a plurality of openings through which the fluid passes are provided in the flow velocity distribution controller asymmetrically with respect to a rotation center. The flow velocity distribution controller is
A cylindrical side wall,
A cylindrical member having a central axis different from that of the measurement pipe part;
A plate-like member arranged radially from the outer periphery of the tubular member to the side wall,
The ultrasonic flowmeter according to claim 1, comprising:   The ultrasonic flowmeter according to claim 4, wherein the tubular member is cylindrical.   The ultrasonic flowmeter according to claim 4, wherein the cylindrical member has a rectangular tube shape. The flow velocity distribution controller is
A small mesh area where the opening area of each hole is small;
A large mesh area with a large opening area of each hole;
The ultrasonic flowmeter according to claim 1, comprising: The center of the small mesh region is different from the central axis of the flow velocity distribution controller;
The large mesh region surrounds the small mesh region;
The ultrasonic flowmeter according to claim 7. Protrusions are provided on the outer circumference of the measurement pipe part,
The ultrasonic flowmeter according to any one of claims 1 to 8, wherein the flow velocity distribution controller is provided with a stepped portion in contact with a projection of the measurement pipe portion. The projection of the measurement pipe part makes a round around the outer periphery of the measurement pipe part,
The step portion of the flow velocity distribution controller makes a round around the outer periphery of the flow velocity distribution controller.
The ultrasonic flowmeter according to claim 9.   The ultrasonic flowmeter according to claim 9 or 10, further comprising a gasket disposed between an outer periphery of the measurement pipe section and a step section of the flow velocity distribution controller.   The ultrasonic flowmeter according to claim 11, wherein the gasket is an O-ring.   A flow velocity distribution controller connected to the measurement piping section of the ultrasonic flowmeter, which is rotatable with respect to the central axis of the measurement piping section, and is relative to the progress of the fluid flowing through the flow velocity distribution controller in cross section. A flow velocity distribution controller provided with a strong resistance region that gives a strong resistance and a weak resistance region that gives a relatively weak resistance to the progress of the fluid.   The flow velocity distribution of the fluid reaching the flow velocity distribution controller is rotated so that the strong resistance region hits a portion where the flow velocity is fast and the weak resistance region hits a portion where the flow velocity is slow. Flow velocity distribution controller.   The flow velocity distribution controller according to claim 13 or 14, wherein a plurality of openings through which the fluid passes are provided asymmetrically with respect to a rotation center. A cylindrical side wall,
A cylindrical member having a central axis different from that of the measurement pipe part;
A plate-like member arranged radially from the outer periphery of the tubular member to the side wall,
The flow velocity distribution controller according to claim 13, comprising:   The flow velocity distribution controller according to claim 16, wherein the cylindrical member is cylindrical.   The flow velocity distribution controller according to claim 16, wherein the cylindrical member has a rectangular tube shape. A small mesh area where the opening area of each hole is small;
A large mesh area with a large opening area of each hole;
The flow velocity distribution controller according to claim 13, comprising: The center of the small mesh region is different from the central axis of the flow velocity distribution controller;
The large mesh region surrounds the small mesh region;
The flow velocity distribution controller according to claim 19.