JP2004101543A - Ultrasonic flow measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve measuring accuracy by devising the flow form of a fluid reaching an ultrasonic propagation path in a flow measuring instrument using ultrasonic signals. <P>SOLUTION: Ultrasonic transmitter-receivers 8, 9 located upstream and downstream of a measuring passage 6 where a measured fluid flows, are arranged in open holes 11, 12, and a propagation path flow regulating body 43 having a regulating part 44 exposed into the flow is provided along the ultrasonic propagation path 13 between the upstream and downstream ultrasonic transmitter-receivers 8, 9. The turbulence of flow is thereby accelerated by the regulating part of the propagation path flow regulating body to make the flow state uniformly turbulent over the whole cross direction region of the ultrasonic propagation path 13. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an ultrasonic flow rate measuring device that measures the flow rate of a gas or liquid by using ultrasonic waves.

Conventionally, as shown in FIG. 44, this type of ultrasonic flow rate measuring device is opposed to a measuring tube 1 through which a fluid flows from one side to the other side, and is inclined at a predetermined angle with respect to a center line on an upstream side. An ultrasonic transmitter / receiver 2a and a downstream ultrasonic transmitter / receiver 2b are provided to face each other. These ultrasonic transmitters / receivers 2a and 2b are housed in concave portions 3a and 3b provided in the measurement tube 1, A flow fluctuation suppressing unit 5 is provided on the inlet side 4.

The flow entering the measuring tube 1 is regulated by the flow fluctuation suppressing unit 5 to reduce the inclination of the streamline in the measuring unit and to suppress the generation of vortices. Fluctuations in the reception level of ultrasonic waves due to reflection or refraction are reduced to prevent deterioration in measurement accuracy (for example, see Patent Document 1).

As another conventional example, as shown in FIG. 45, a pair of ultrasonic transceivers 2a and 2b are arranged upstream and downstream of the side surface of the measurement tube 1, and these ultrasonic transceivers 2a and 2b are connected to the measurement tube 1 In addition to being accommodated in the concave portions 3a and 3b provided in the above, the bulk ultrasonic transmitting member 3c is provided in the concave space of the concave portions 3a and 3b to prevent the flow entering the concave portions 3a and 3b, and to measure the flow rate with high accuracy. (For example, see Patent Document 2).
JP-A-11-351926 JP-A-63-26537

However, in the conventional configuration as shown in FIG. 44, the flow fluctuation suppressing unit 5 reduces the turbulence of the flow in the measurement unit and the recesses 3a and 3b of the measurement tube 1 and reduces the deterioration of the measurement accuracy. When the flow rate flowing through 1 increases, the fluid flows into the concave portions 3a and 3b to generate a vortex, so that the turbulence of the flow between the ultrasonic transceivers 2a and 2b increases, and the ultrasonic wave is reflected or refracted by the increased vortex. Since the reception level of the ultrasonic wave is reduced, there is a problem that it is difficult to reduce the drive input of the ultrasonic transceivers 2a and 2b.

Further, in the configuration as shown in FIG. 45 in which the bulk ultrasonic transmission members 3c are provided in the concave portions 3a and 3b, propagation loss occurs when ultrasonic waves propagate inside the bulk ultrasonic transmission members 3c. The problem that the transmission output and the reception sensitivity of the ultrasonic wave are reduced, and the solid state propagation inside the bulk ultrasonic transmission member 3c lowers the straightness and makes it difficult to radiate in the direction of the opposed ultrasonic transducer. was there. For this reason, there is a problem in terms of reducing power consumption if the battery is to be used for a long period of, for example, 10 years with a small battery capacity, such as a gas meter for measuring household fuel gas such as city gas or LPG.

The present invention has been made to solve the above-described problems, and reduces the occurrence of turbulence and eddies between the ultrasonic transceivers to increase the reception level of the ultrasonic wave, thereby increasing the measurement accuracy and the upper limit value of the flow rate measurement, and increasing the ultrasonic wave. This is to reduce the drive input power to the transceiver.

The ultrasonic flow rate measuring device according to the present invention includes a propagation path flow restricting body that is disposed along the ultrasonic propagation path between the upstream and downstream ultrasonic transceivers and that has a restricting portion exposed in the flow. The turbulence of the flow is promoted by the restricting portion of the propagation path flow regulating member on the upstream side of the ultrasonic wave propagation path.

According to the ultrasonic flow rate measuring device of the present invention, the turbulence of the flow is promoted by the regulating portion of the propagation path flow regulating body, and the flow state is uniformly turbulent throughout the width direction of the ultrasonic propagation path, It is possible to prevent the range of the error from being increased by the correction coefficient, thereby significantly improving the measurement accuracy.

An embodiment of the present invention provides a measurement channel through which a fluid to be measured flows, an ultrasonic transceiver provided on the upstream side and the downstream side of the measurement channel, and the ultrasonic transceiver facing the measurement channel. An aperture hole, a propagation path flow regulating body having a regulating section disposed along an ultrasonic wave propagation path between the upstream and downstream ultrasonic transceivers and exposed in the flow, between the ultrasonic transceivers; A measurement control unit that measures the propagation time of the ultrasonic wave, and a calculation unit that calculates the flow rate based on a signal from the measurement control unit. Therefore, the turbulence of the flow is promoted by the restricting portion of the road flow restricting body, and the flow state is uniformly turbulent over the entire width direction of the ultrasonic wave propagation path.

Of course, it is more effective if an inflow restrictor is provided in the opening that allows the ultrasonic transceiver to face the measurement flow path to reduce the flow of the fluid to be measured into the opening. It is conceivable that the inflow suppressing member provided in the opening hole is a flow deflector or an opening sealing portion having at least one ultrasonic transmission port.

Further, the propagation path flow restricting body may be arranged on the upstream side and the downstream side of the ultrasonic wave propagation path. In this case, the upstream and downstream propagation path flow restricting bodies may be integrated via a connecting portion. Good.

The propagation path flow restrictor changes the installation distance from the ultrasonic propagation path according to the type of the fluid to be measured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Example 1)
In FIG. 1, reference numeral 6 denotes a measurement flow path surrounded by a flow path wall 7, and reference numerals 8 and 9 denote upstream and downstream sides which are attached to the flow path wall 7 via a vibration transmission suppressor 10 so as to face each other. The ultrasonic transmitter / receiver 8 on the upstream side and the ultrasonic transmitter / receiver 9 on the downstream side are arranged at a distance L and at an angle θ with respect to the flow direction of the measurement flow path 6.

Nos. 11 and 12 are upstream and downstream opening holes that allow the ultrasonic transceivers 8 and 9 to face the measurement flow path 6, and are provided as depressions in the flow path wall 7. Reference numeral 13 denotes an ultrasonic wave propagation path (indicated by a two-dot chain line) in which ultrasonic waves transmitted between the opposing ultrasonic wave transmitters and receivers 8 and 9 propagate directly to the ultrasonic wave transmitter / receiver on the other side without being reflected on the wall surface.

Reference numeral 14 denotes a first inflow suppressing member provided in the upstream opening 11 to reduce the flow of the fluid to be measured into the upstream opening 11, and 15 denotes a downstream inflow opening 12 provided in the downstream opening 12. The first inflow suppressing body 15 that reduces the flow of the fluid to be measured into the opening hole 12. Reference numeral 16 denotes a second inflow suppressor provided on the upstream side of the ultrasonic wave propagation path 13 to reduce the flow of the fluid to be measured into the opening holes 11 and 12 on the upstream and downstream sides. It is installed so as to fit into the part 7a.

FIG. 2 shows the first inflow suppressing member 15 provided in the downstream opening hole 12, and reference numeral 21 denotes an opening sealing portion having a number of ultrasonic wave passage openings 22 through which ultrasonic waves can pass. The sealing portion 21 is disposed so as to cross the ultrasonic wave propagation path 13 so as to cover the opening hole 12 and is provided so as to be flush with the measurement flow path surface 6a, thereby preventing the fluid to be measured from flowing into the opening hole 12. I have.

Here, a mesh or the like having a large number of ultrasonic wave passage openings 22 through which ultrasonic waves can pass as the opening hole sealing portion 21 is directly arranged on the measurement flow path surface 6a of the measurement flow path 6 of the opening hole 12 so as not to disturb the flow. Are provided flush with each other.

FIG. 3 shows a first inflow suppressing body 14 provided in the upstream opening hole 11, which is protruded from the flow path wall 7 and has a smooth protrusion provided near the upstream side of the upstream opening hole 11. A flow deflector 14a and a guide surface 14b having an increased protrusion height are provided upstream of the flow deflector 14a.

The second inflow suppressor 16 has a direction restricting portion 16a for adjusting the flow direction of the fluid to be measured and a fluctuation suppressing portion 16b for making the flow velocity distribution uniform or reducing flow pulsation. The direction restricting portion 16a is provided with a partition wall for finely dividing the cross section of the measurement flow channel 6, and the fluctuation suppressing portion 16b has a short flow direction length and a large number of fine It has a communication passage having a shape.

Reference numeral 17 denotes an upstream bent portion that communicates with an on-off valve (not shown) provided on the upstream side of the measurement flow channel 6, and reference numeral 18 denotes a downstream portion that communicates with an outlet (not shown) provided on the downstream side of the measurement flow channel 6. The flow path is formed compact by the bent parts 17 and 18. Reference numeral 19 denotes a measurement control unit connected to the ultrasonic transceivers 8 and 9 for transmitting and receiving ultrasonic waves. Reference numeral 20 denotes a calculation unit that calculates a flow rate based on a signal from the measurement control unit 19 and calculates a flow rate.

Next, the flow rate measurement operation using ultrasonic waves will be described. In the ultrasonic wave propagation path 13 of the measurement flow path 6, ultrasonic waves are transmitted and received between the ultrasonic transceivers 8 and 9 across the measurement flow path 6 by the operation of the measurement control unit 19. That is, the propagation time T1 until the ultrasonic wave emitted from the upstream ultrasonic transceiver 8 is received by the downstream ultrasonic transceiver 9 is measured. On the other hand, the propagation time T2 until the ultrasonic wave emitted from the downstream ultrasonic transceiver 9 is received by the upstream ultrasonic transceiver 8 is measured.

流量 Based on the propagation times T1 and T2 measured in this way, the flow rate is calculated by the calculation unit 20 by the following calculation formula.

Now, it is assumed that the flow velocity of the fluid to be measured in the longitudinal direction of the measurement flow path 6 is V, the angle between the flow direction and the ultrasonic wave propagation path 13 is θ, the distance between the ultrasonic transceivers 8 and 9 is L, Assuming that the sound velocity of the measurement fluid is C, the flow velocity V is calculated by the following equation.

T1 = L / (C + Vcosθ)
T2 = L / (C−Vcos θ)
V = (L / 2 cos θ) ((1 / T1) − (1 / T2))
Since θ and L are known, the flow velocity V can be calculated from the values of T1 and T2. Now, assuming that the flow rate of air is measured, assuming an angle θ = 45 degrees, a distance L = 70 mm, a sound velocity C = 340 m / s, and a flow velocity V = 8 m / s, T1 = 2.0 × 10 ⁻⁴ seconds, T2 = 2.1 × 10 ⁻⁴ seconds, and instantaneous measurement can be performed.

Next, from the cross-sectional area S orthogonal to the flow direction of the measurement flow path 6, the flow rate Q is given by: Q = KVS
Here, K is a correction coefficient in consideration of the flow velocity distribution in the cross-sectional area S. In this way, the flow rate is obtained by the arithmetic unit 20.

Next, a description will be given of a flow state and a measurement operation in the measurement flow path of the ultrasonic flow measurement device. The measurement flow is generated while the drift or the pulsation of the flow is generated due to the flow of the fluid to be measured being enlarged / reduced in the cross-sectional area of the flow passage at an on-off valve (not shown) provided on the upstream side of the measurement flow passage 6 or flowing through the bent portion 17. Enter Road 6.

Then, the flow in the measurement flow path 6 is rectified by the direction restricting portion 16 a of the second inflow suppressing body 16 provided on the upstream side of the ultrasonic wave propagation path 13 in a direction hard to flow into the opening holes 11 and 12. At the same time, the turbulence of the flow is reduced, and the turbulence due to flow fluctuations such as pulsation is reduced by the fluctuation suppressing portion 16b so that the flow into the openings 11 and 12 is further suppressed.

The fluctuation suppressing portion 16b can reduce the pressure loss due to the fluctuation suppressing portion 16b by reducing the mesh, foam, microporous plate, nonwoven fabric, or the like having a high aperture ratio in the flow direction, without increasing the pressure loss. In addition to reducing flow fluctuations in the measurement flow path, it also reduces fluctuations in flow even in areas with high flow velocities, thereby suppressing fluctuations in the propagation time of ultrasonic waves and increasing the upper limit of measurable flow velocity or flow rate. It can be enlarged and the measurement accuracy can be further improved.

Next, in the opening hole 12 opened in front of the ultrasonic transmitter / receiver 9 on the downstream side where a strong vortex is likely to be generated because it intersects the measurement flow path at an acute angle, the flow rectified by the second inflow suppressing body 16 is formed. On the other hand, an opening sealing portion 21 such as a mesh having a number of ultrasonic wave passage openings 22 through which ultrasonic waves can pass is arranged on the measurement flow path surface 6a of the measurement flow path 6 and is flush with each other so as not to disturb the flow. Since it is provided, the effect of suppressing the inflow of the fluid to be measured into the opening hole 12 on the downstream side can be further enhanced, and the vortex and the disturbance of the flow in the ultrasonic wave propagation path 13 can be greatly reduced.

On the other hand, in the upstream opening hole 11, as shown by the arrow in FIG. 3, the first inflow suppressing body 14 formed by the protruding flow deflector 14 a provided near the upstream side of the opening hole 11. 11 is further reduced, and turbulence such as eddies is reduced and stabilized. Since the upstream opening hole 11 intersects the measurement flow path 6 at an obtuse angle, the intensity of the vortex is smaller than that of the downstream opening hole 12 and its adverse effect is small, and it is not always necessary to provide the first inflow suppressing body 14. The flow can be further stabilized by providing the first inflow suppressing body 14 in the opening hole 11 on the upstream side. Further, the first inflow suppressing body 14 is formed integrally with the flow path wall 7 so that the configuration is simplified and the cost can be reduced.

Ultrasonic waves are transmitted and received between the ultrasonic transceivers 8 and 9 with respect to the ultrasonic wave propagation path 13 in which the flow is stabilized in this way, and the reception level of the ultrasonic waves is increased to realize highly accurate flow velocity measurement. It is possible to increase the upper limit of the flow rate that can be measured by reducing the attenuation of the ultrasonic wave due to the flow fluctuation.

Further, since the reception level of the ultrasonic wave can be improved by the stabilization of the flow, not only can the power consumption for transmitting the ultrasonic wave be reduced, but also by disposing the opening sealing portion 21 only in the opening 12 on the downstream side. The power consumption can be reduced by reducing the attenuation of the ultrasonic waves caused by passing through the opening hole sealing portion 21 and reducing the driving electric input to the ultrasonic transceivers 8 and 9, as in a home gas meter. When driven by a battery, the battery can be continuously used for a long time with a small battery capacity.

FIG. 4 is a cross-sectional view of an ultrasonic flow rate measuring device showing another first inflow suppressing body. The same members and the same functions as those in the embodiment of FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description is omitted. The following description focuses on the differences. An opening sealing portion 21a having an ultrasonic wave passage 22 is provided in the downstream opening 12 as the first inflow suppressing body 15, similarly to the embodiment of FIG. An opening sealing portion 21b having an ultrasonic passage 22 is provided as the first inflow suppressor 14.

Both opening hole sealing portions 21a and 21b are provided flush with the measurement channel surface. By providing the opening sealing portions 21a and 21b in both the upstream opening 11 and the downstream opening 12, the flow of the fluid into the opening is suppressed and the vortex and the disturbance of the flow are prevented. As a result, not only can the measurement accuracy be improved, but also the measurement can be performed with improved accuracy even for a pulsating flow accompanied by instantaneous backflow.

Furthermore, since the disturbance of the flow in the opening holes 11 and 12 can be greatly reduced, the refraction and reflection of the ultrasonic wave due to the disturbance can be reduced, and the transmission and reception of the ultrasonic wave having excellent S / N characteristics can be realized, and the transmission output can be reduced. The power consumption can be reduced by reducing the drive input.

Further, another embodiment of the opening hole sealing portions 21a and 21b will be described without using the drawings. Since the upstream opening 11 intersects the measurement flow path 6 at an obtuse angle and the vortex generation intensity is low, the opening ratio of the opening sealing portion 21b provided in the upstream opening 11 is the downstream opening. Even if the opening ratio is larger than the opening ratio of the opening sealing portion 21a provided in the opening 12, the effect of suppressing the inflow can be expected.

Therefore, in the present embodiment, the opening ratio of the upstream opening sealing portion 21b is larger than that of the downstream opening sealing portion 21a. For this reason, since the upstream opening sealing portion 21b has a large area of the ultrasonic wave passage opening, the propagation loss of the ultrasonic wave can be reduced as compared with the downstream opening sealing portion 21a.

Thus, the propagation loss of the ultrasonic wave can be reduced as compared with the case where the opening hole sealing portions having the same opening ratio are used on the upstream side and the downstream side, and the power consumption can be reduced by reducing the drive input to the ultrasonic transceiver.

FIG. 5 shows another embodiment of the first inflow suppressing body 15 provided in the downstream opening hole 12. Reference numeral 23 denotes an upstream side of the downstream opening hole 12 provided with the opening sealing portion 21. The flow deflector 23 is formed in a plate shape or a wing shape, and regulates the flow direction so that the fluid to be measured does not flow into the opening 12. As described above, the opening hole 12 includes both the opening hole sealing portion 21 and the flow deflector 23 as the first inflow suppressing member 15.

Here, the flow direction is regulated by the flow deflector 23 with respect to the opening hole 12 to reduce the flow toward the inside of the opening hole 12, and the flow which is going a little further is reduced by the opening hole sealing portion 21. The flow into the opening 12 is prevented to prevent turbulence such as a vortex in the opening 12, and the flow in the ultrasonic wave propagation path 13 is stabilized, so that the measurement accuracy can be further improved.

In addition, since the flow deflecting body 23 can reduce the flow colliding with the opening hole sealing portion 21, even if a fine powdery foreign substance such as dust is contained in the fluid to be measured, the foreign matter entering the opening hole sealing portion 21 can be reduced. Can be reduced. For this reason, the specification of the opening hole sealing portion 21 that allows the transmission of the ultrasonic wave is considered first, and the degree of freedom of selection or setting is improved, and the transmission of the ultrasonic wave is further increased, so that high sensitivity can be achieved. Low power consumption or high accuracy can be realized. The measurement accuracy can be further improved by making the same in the opening hole 11 on the upstream side.

FIG. 6 shows another embodiment of the opening hole sealing portion. Reference numeral 24 denotes a mesh body having a mesh-like ultrasonic wave passing port 22. It is provided on the upper surface along the measurement flow path surface 6a. Here, the flow direction of the fluid to be measured in the measurement flow path 6 is set to be substantially horizontal, and the measurement flow path surface 6a provided with the opening holes 11 and 12 is set to be substantially vertical. With respect to the installation posture of the measurement flow path, the mesh body 24 is formed by an inclined mesh portion 25 having an inclination α with respect to the horizontal so that there is no mesh portion arranged horizontally.

Here, if the fluid to be measured continues to flow while containing fine powdery foreign substances such as dust, the fluid may adhere to the net 24 provided in the opening hole 12. However, since the reticulated body 24 is formed of the inclined mesh portion 25 inclined with respect to the horizontal, the fine powdery foreign matter adhered to the sliding is promoted to slide down along the inclination. Therefore, clogging of the mesh body 24 due to the deposition of the fine powdery foreign matter adhered thereto can be prevented, and the passage of ultrasonic waves can be ensured, and stable measurement of the flow velocity and flow rate can be maintained. Here, the downstream side opening hole 12 has been described, but the same applies to the upstream side opening hole 11.

FIG. 7 is a sectional view taken along the line AA of the measurement flow channel shown in FIG. The measurement flow path 6 is formed by a flow path wall 7 in which a cross-section height is H and a flow path wall 7b having a concave portion and a flow path wall 7c having a convex portion are fitted. This rectangular cross section enables a two-dimensional flow in the measurement flow path 6, and the fluctuation of the flow which is likely to occur at the corner of the rectangular cross section is suppressed by the second inflow suppressing body 16, so that the measurement flow path 6 Two-dimensional flow in the inside can be promoted. Furthermore, since the height H of the measurement flow path 6 between the ultrasonic transceivers is constant, the average flow velocity of the fluid can be measured with high accuracy by increasing the ratio of the measurement area in which the ultrasonic wave propagates to the total cross-sectional area of the flow path.

In addition, in order to ensure the durability of the production equipment such as a mold as in the case where the flow path wall 7 is formed by die casting or the like, a substantially rectangular shape having rounded corners (corners R) in a rectangular cross section is also used. Needless to say, it is included in the rectangular cross section.

FIG. 8 shows the opening shape of the opening hole 12 on the measurement channel surface 6a of the measurement channel 6 having the rectangular cross section shown in FIG. A direction substantially perpendicular to the direction (indicated by an arrow in the figure) is defined as one side 12a, and a direction substantially parallel to the flow direction is defined as a rectangle having the other side 12b.

For this reason, in the measurement flow path 6, the opening length of the opening hole 12 in the flow direction becomes the same at any height position H as shown by D in the figure, and ultrasonic waves are transmitted uniformly in the height H direction. The measurement can be performed with high accuracy by uniformly measuring the inside of the measurement channel 6. Further, the length D in the flow direction of the opening can be made shorter than in the case of a shape having a round hole or an arc-shaped portion having the same opening area, so that the flow disturbance occurs in the measurement flow path 6 and the flow into the opening hole 12. And the measurement accuracy can be improved.

Here, the case of the downstream opening hole 12 is shown, but it goes without saying that the measurement accuracy can be further improved by making the opening shape of the upstream opening hole 11 on the measurement flow path surface 6a rectangular. .

As described above, according to the ultrasonic flow measurement device of the present embodiment, the flow of the fluid to be measured into the opening hole 12 is reduced by the first inflow suppressing body 15 provided at least in the opening hole on the downstream side, The turbulence of the flow between the transceivers 8 and 9 can be significantly reduced, the measurement accuracy can be increased, and the upper limit value of the flow rate can be increased, and the first inflow suppressor 15 has the ultrasonic transmission port 22. The opening hole sealing portion 21 can further enhance the effect of suppressing the inflow of the fluid to be measured into the opening hole and stabilize the flow in the opening hole. By disposing the sealing portion 21 only in the opening 12 on the downstream side, attenuation of ultrasonic waves can be further reduced, drive input to the ultrasonic transceiver can be reduced, power consumption can be reduced, and measurement accuracy can be improved. .

In addition, the first inflow suppressing member 14 provided in the opening 11 on the upstream side includes an opening sealing portion 21b having an ultrasonic transmission port 22 to prevent fluid from flowing into the opening on the upstream and downstream sides. A significant reduction can be realized, the upper limit value of the flow rate measurement can be increased, and the measurement accuracy can be improved even for a flow accompanied by a backflow.

Further, the opening ratio of the opening sealing portion 21b provided in the opening 11 on the upstream side is made larger than the opening ratio of the opening sealing portion 21a provided in the opening 12 on the downstream side, so that the propagation loss of the ultrasonic wave is reduced. , The upper limit value of the flow rate measurement can be improved and the measurement accuracy for the backflow can be improved, and the power consumption can be reduced by reducing the drive input to the ultrasonic transceiver.

Further, the first inflow suppressing body 15 includes an opening hole sealing portion 21 having an ultrasonic transmission port 22 and a flow deflector provided near the opening hole 11 or 12, so that the flow of the fluid to be measured into the opening hole is achieved. By further improving the suppression effect, the measurement accuracy can be further improved, and the flow deflector can reduce the adhesion of foreign substances such as dust to the opening hole sealing portion. It is possible to select the ultrasonic wave with high flexibility without putting the ultrasonic wave first, and it is possible to realize a device with lower power consumption or higher sensitivity and higher measurement accuracy by further increasing the ultrasonic wave permeability.

In addition, the opening hole sealing portion 21 is formed as a reticulated mesh member 24 having an inclination with respect to the horizontal, and is inclined with respect to the horizontal so as to promote the fall of fine powder such as dust attached to the inclined mesh portion 25 to be deposited. By reducing the amount and preventing clogging of the mesh body, propagation of ultrasonic waves can be secured, stable measurement accuracy can be maintained for a long time, and durability and reliability can be improved.

The cross section orthogonal to the flow of the measurement flow path 6 is rectangular, and the ratio of the measurement area in the measurement cross section can be increased by forming a rectangular cross section, so that the flow is measured from the upstream side to the downstream side of the ultrasonic wave propagation path 13 under the same conditions. What can be done and the two-dimensional flow of the flow in the measurement flow path 6 can be promoted, so that the average flow velocity of the fluid can be measured with high accuracy. Further, the provision of the second inflow suppressing body 16 can further promote the two-dimensional flow.

The shape of the opening holes 11 and 12 to the measurement flow path 6 is a shape having one side in a direction substantially orthogonal to the flow direction of the measurement flow path 6. Ultrasonic waves can be transmitted and received evenly in the height direction of the measurement flow path 6, and the size of the opening in the measurement flow path in the flow direction can be shortened, so that flow disturbance due to the opening is further reduced. As a result, the measurement accuracy can be further improved.

In the present embodiment, the case where the bent portions 17 and 18 are bent in the direction of the width W of the measurement flow channel 6 is shown. However, the bending direction of the bent portions 17 and 18 is the same in the direction of the height H of the measurement flow channel 6. It goes without saying that the bending direction may be any direction as well as the bending direction of the bent portion 17 and the bent portion 18 may be different.

In addition, the effect of suppressing the flow of the fluid into the opening hole has been described as an effect of the first inflow suppressing members 14 and 15, but the viscosity of the fluid flowing through the measurement flow path induces the fluid in the opening hole to enter the opening hole. Needless to say, the effect of suppressing the attraction to the generation of the vortex can be expected.

(Example 2)
9, the same members and the same functions as those in the embodiment of FIGS. 1 to 8 are denoted by the same reference numerals, detailed description thereof will be omitted, and different points will be mainly described.

Reference numeral 26 denotes a drift suppression body provided in an introduction portion 27 serving as an inlet of the measurement flow channel 6 and having a large number of fine flow openings 26a. This drift suppression body 26 is used when the flow velocity distribution flowing into the introduction portion 27 has a bias. The flow velocity distribution is equalized and supplied to the measurement flow path 6.

Reference numeral 28 denotes a valve block having a connection port 29 connected to the upstream side of the bent portion 17 and opening to the introduction portion 27. The valve block 28 is provided with an on-off valve 32 having a valve element 31 facing the valve seat 30. ing. Reference numeral 33 denotes a fluid inlet provided upstream of the valve seat 30 and through which fluid flows. An outlet block 34 is connected to the downstream side of the bent portion 18 and has a fluid outlet 35 from which fluid flows out. Reference numeral 36 denotes a spring for urging the valve element 31 in the direction of the valve seat 30, and reference numeral 37 denotes a drive unit such as a solenoid or a motor for driving the valve element 31 to open or close the on-off valve 32.

Next, the operation of the ultrasonic flow measurement device will be described. With the opening of the on-off valve 32, the fluid to be measured flows in from the fluid inlet 33, passes through the valve seat 30, flows into the inlet 27 through the connection port 29. The flow that has flowed into the introduction portion 27 is affected by the piping on the upstream side of the fluid inlet 33 and passes through the bent passage of the valve block 28, so that the flow direction and the uniformity of the flow velocity distribution are reduced, and the flow is pulsated. It is in an irregular state.

However, by passing through the fine flow opening 26a of the drift preventing body 26 provided in the introduction portion 27, the flow direction and the non-uniformity of the flow velocity distribution are improved, and the pulsation of the flow is reduced, and a stable flow is obtained. And flows into the measurement channel 6.

As described above, the flow rate distribution in the cross section of the measurement flow path 6 becomes uniform in the measurement flow path 6 due to the direction restricting portion 16 a of the second inflow suppressing body 16, and the flow is rectified in the direction in which the flow hardly flows into the opening holes 11 and 12. At the same time, the fluctuation of the flow such as pulsation is further reduced by the fluctuation suppressing portion 16b and flows into the ultrasonic wave propagation path 13, and the upstream and downstream opening holes 11 and 12 are provided near the upstream side. The first inflow suppressors 14 and 15 reduce the inflow of the flow into the opening holes 11 and 12.

Thus, the ultrasonic wave is transmitted and received between the ultrasonic transceivers 8 and 9 with respect to the ultrasonic wave propagation path 13 in which the flow is further stabilized irrespective of the shape of the pipe on the upstream side, so that a more accurate flow velocity measurement can be performed. This can be realized, and the upper limit of the flow rate that can be measured by reducing the attenuation of the ultrasonic wave due to the fluctuation of the flow can be further increased.

FIG. 10 is a plan view of the introduction portion 27, in which the drift suppression body 26 is disposed over the entire region of the introduction portion 27, and 29a is provided with the on-off valve 32 arranged in the left-right direction of the drawing as shown in FIG. This is the first opening position of the connection port 29 when provided on the left side of the paper (indicated by a two-dot chain line). Reference numeral 29b denotes the on-off valve 32 arranged in the front and back direction of the paper of FIG. The second opening position of the connection port 29 in the case where it is provided (indicated by a two-dot chain line) is shown.

The cross-sectional area Sa of the introduction part 27 is a rectangle of the width W and the height H of the measurement channel 6 so that both the first opening position 29a and the second opening position 29b can be arranged in the introduction part 27. As a cross section larger than the cross sectional area Sb (see FIG. 11) (Sa> Sb), the installation area of the drift suppression body 26 is increased. For this reason, the pressure loss of the fluid to be measured by the drift suppression body 26 can be reduced, and the first and second opening positions 29 a and 29 b are biased with respect to the introduction portion 27 for various arrangements of the valve block 28. Even if there is, the flow distribution can be equalized by the fine flow openings 26 a of the drift suppressing body 26 and flow into the measurement flow path 6. Therefore, even if the flow path shape and the pipe shape on the upstream side of the measurement flow path 6 such as the valve block 28 are different, the measurement accuracy can be secured, so that the degree of freedom of installation can be improved.

Further, as shown in FIG. 11, the opening dimension Ta of the flow opening 26 a having the fine opening provided in the drift suppressing body 26 is equal to the opening of the flow opening 16 c of the fine opening of the fluctuation suppressing portion 16 b of the second inflow suppressing body 16. It is smaller than the dimension Tb (Ta <Tb). For this reason, the action of equalizing the flow pulsation and the deviation of the flow velocity distribution can be stronger in the drift suppression body 26 than in the second inflow suppression body 16, and by providing the drift suppression body 26, the measurement flow path 6 can be further enhanced. It can supply a stable flow.

Therefore, even if the connection port 29 into which the fluid on the upstream side flows is biased, the measurement can be performed with higher accuracy by making the fluid flow into the measurement flow path 6 more evenly, and the flowing fluid has pulsation. However, the flow with reduced pulsation can be supplied to the measurement flow path 6, and the measurement accuracy can be improved even for the pulsation flow.

In addition, by setting the flow opening 26a of the drift suppression body 26 to have an opening size smaller than the flow opening 16c of the fluctuation suppression unit 16b of the second inflow suppression body 16, foreign matter such as dust and dust enters the measurement flow path 6. Can be reduced, the measurement operation can be made reliable, and the reliability can be improved. Furthermore, by making the cross-sectional area Sa of the drift suppressing body 26 larger than the cross-sectional area Sb of the measurement flow path 6, the pressure loss of the fluid to be measured can be reduced, and the measurement characteristics can be improved even if foreign substances adhere to the drift suppressing body 26. Drop can be prevented.

FIG. 12 shows another embodiment of the drift suppression body 26, in which a first drift suppression body 26 b provided in the introduction section 27 and a second drift provision section 38 provided in the downstream side of the measurement flow path 6. And the second drift suppression body 26c has many fine flow ports 26d like the first drift suppression body 26b.

In this configuration, when there is flow fluctuation or inflow bias on the upstream side of the measurement flow path 6, the first pulsation suppressing body 26b exerts the above-described pulsation reduction and drift suppression effects, and the downstream of the measurement flow path 6 Even if there is a cause of flow fluctuation or deviation on the side, the pulsation can be reduced and the drift suppressing effect can be exerted by the second drift suppression body 26c to improve the measurement accuracy, and the upstream and downstream of the measurement flow path 6 can be improved. Stable measurement can be realized irrespective of the shape of the flow path on the side and the state of the piping, and the degree of freedom in installing the measuring device can be further improved.

Furthermore, even when backflow occurs momentarily due to pulsation, measurement with high accuracy can be performed, and stable measurement can be performed regardless of the position of the pulsation source. In addition, the opening size of the flow opening 26d of the second drift suppression body 26c is made smaller than the flow opening 16c of the second inflow suppression body 16, or the cross-sectional area of the lead-out portion 38 in which the second drift suppression body 26c is arranged is reduced. By making it larger than the cross-sectional area of the measurement flow path 6, the above-described effects can be exerted similarly to the case of the introduction part 27, and the measurement accuracy can be improved, the degree of freedom in installation can be improved, and the reliability against foreign substances can be improved.

As described above, according to the second embodiment, the drift suppression body 26 having the flow opening 26a having the fine opening is provided in the introduction portion 27 arranged on the upstream side of the measurement flow path 6 so that the shape of the flow path on the upstream side can be improved. By supplying a stable flow to the measurement flow path 6 regardless of the pipe shape, disturbance of the flow between the ultrasonic transceivers 8 and 9 can be reduced, and the upper limit of the measurable value can be further increased and the measurement accuracy can be further improved. In addition, stable measurement can be realized irrespective of the shape of the flow path on the upstream side of the measurement flow path 6 and the state of the piping, and the degree of freedom of installation of the measurement device can be improved.

In addition, the introduction part 27 arranged on the upstream side of the measurement flow path 6 and the drift prevention bodies 26b and 26c having the flow openings 26a and 26d having fine openings are provided in the outlet part 38 on the downstream side to reduce pulsation accompanied by backflow. Regardless of the fluid to be measured having the pulsation source on the downstream side, the turbulence of the flow between the ultrasonic transceivers 8 and 9 can be reduced by supplying a stable flow to the measurement channel 6. The possible upper limit value can be further increased and the measurement accuracy can be further improved, and furthermore, stable measurement can be realized regardless of the flow path shape or piping state or pulsation source on the upstream or downstream side of the measurement flow path 6, The degree of freedom of installation of the measuring device can be further improved.

In addition, the cross-sectional area of the introduction part 27 or the lead-out part 38 is made larger than the cross-sectional area of the measurement flow path 6, the installation cross-sectional area of the drift suppression body 26 is increased, and the pressure loss of the drift suppression body 26 is reduced. The increase in loss can be prevented, and the introduction section 27 or the exit section 38 has a large cross section, so that the shape of the introduction section or the exit section does not change even if the flow path shape or the pipe shape on the upstream or downstream side is different. A measuring device that can be mounted and has a high degree of freedom in installation can be realized.

開口 The size of the opening of the flow opening of the drift suppression body 26 is smaller than the size of the opening of the flow opening provided in the second inflow suppression body 16. And even if the upstream or downstream connection port is arranged eccentrically, it is possible to perform measurement with high accuracy by flowing the fluid evenly in the measurement flow path, and even if the fluid to be measured has pulsation, a small opening The measurement flow channel can be supplied to the measurement channel as a flow with reduced pulsation by the flow port having the dimension, and the measurement accuracy can be improved even for the pulsation flow. Furthermore, the small-sized flow opening of the drift suppression body can reduce intrusion of dust, dust, and the like into the measurement section, and can increase the reliability of the measurement operation in the measurement flow path.

In the second embodiment, the case where the bent portions 17 and 18 are bent in the direction of the width W of the measurement channel 6 is shown. However, the bending direction of the bent portions 17 and 18 is the direction of the height H of the measurement channel 6. Needless to say, the bending direction may be any direction, and the bending directions of the bent portion 17 and the bent portion 18 may be different.

(Example 3)
13, the same members and the same functions as those in the embodiment of FIGS. 1 to 12 are denoted by the same reference numerals, detailed description thereof will be omitted, and different points will be mainly described.

Reference numeral 39 denotes a first inflow suppressor that reduces the flow of the fluid to be measured into the opening hole 11 even if the fluid to be measured flows in the measurement flow path 6 in either the forward direction or the reverse direction. A flow deflector 40a provided near the upstream and a flow deflector 40b provided near the downstream of the opening 11 are provided. Reference numeral 41 denotes a second inflow suppressor provided on the downstream side of the ultrasonic wave propagation path 13. The second inflow suppressor 41 is provided with a direction regulating portion 41a for adjusting the flow direction of the fluid to be measured and a uniform or uniform flow velocity distribution. And a fluctuation suppressing unit 41b for reducing the pulsation of the light. Further, a first inflow suppressing body 15 including an opening hole sealing portion 21 having the above-mentioned ultrasonic wave passage 22 is provided in the downstream opening hole 12, and a direction restriction is provided on the upstream side of the ultrasonic wave propagation path 13. A second inflow suppressing body 16 including a portion 16a and a fluctuation suppressing portion 16b is provided.

Next, a description will be given of a flow state and a measurement operation in the measurement flow path of the ultrasonic flow measurement device. First, in the case where the fluid to be measured flows in the measurement flow path 6 in the forward direction, as described in the first embodiment, even if the flow having the drift or the pulsation of the flow flows into the measurement flow path 6, the second flow is performed. The flow is stabilized in the ultrasonic wave propagation path 13 by the inflow suppressing body 16 or the first inflow suppressing bodies 39 and 15 to suppress the inflow to the opening holes 11 and 12, thereby improving the measurement accuracy and measuring. The upper limit is improved.

Next, even if a reverse flow flows into the measurement flow path 6 such as when an instantaneous reverse flow occurs due to pulsation, when the flow direction changes, or when the flow flows in the reverse direction due to incorrect connection of piping, etc. The inflow suppressors 15 and 39 or the second inflow suppressor 41 can realize a flow that suppresses the inflow to the opening holes 11 and 12 with respect to the backward flow as in the case of the forward flow. Therefore, even when an instantaneous reverse flow occurs due to a flow with pulsation, the flow of the fluid to be measured into the opening hole is reduced as in the case of the forward flow, and the turbulence of the flow between the ultrasonic transceivers 8 and 9 is reduced. This can greatly reduce the measurement accuracy, increase the measurement accuracy, and increase the upper limit value at which the flow rate can be measured. In addition, measurement can be performed with high accuracy even in the case of a reverse flow, so that the degree of freedom of installation is high and convenience can be improved.

The first inflow suppressing member 39 has an example in which the projections formed by the flow deflectors 40a and 40b provided near the upstream side and the downstream side of the opening hole 11 are arranged on the opening surface. , 12 may be provided so as to surround the entire circumference (not shown). Further, as a configuration using the opening hole sealing portion described above with reference to FIG. 2 or FIG. Measurement accuracy can be improved even for a large flow in the opposite direction, and convenience can be improved.

FIG. 14 shows another embodiment of the first inflow suppressing body, which will be described in the case where the first inflow suppressing body is installed in the opening hole 12 on the downstream side. Reference numeral 23 denotes a flow deflector provided near the upstream side of the opening 12 having the opening sealing portion 21, and reference numeral 42 denotes a flow deflector provided near the downstream side of the opening 12. The flow deflectors 23 and 42 are formed in a plate shape or a wing shape, and regulate the flow direction so that the fluid to be measured does not flow into the opening hole 12. As described above, in the present embodiment, the first inflow suppressing member includes the flow deflecting members 23 and 42 on the upstream and downstream sides of the opening hole sealing portion 21 and the opening holes 11 and 12, respectively.

Here, with respect to the fluid flowing in the measurement flow path 6 in the forward direction, the flow direction is regulated by the flow deflector 23 disposed on the upstream side of the opening hole 12 to reduce the flow toward the inside of the opening hole 12, and With respect to the fluid flowing in the path 6 in the opposite direction, the flow direction is restricted by the flow deflector 42 disposed downstream of the opening hole 12 to reduce the flow toward the inside of the opening hole 12, and the opening hole 12 The flow toward the opening is prevented by the opening sealing portion 21 from flowing into the opening 12 to prevent turbulence such as a vortex in the opening 12 from occurring. Therefore, the measurement accuracy can be further improved by stabilizing the flow in the ultrasonic wave propagation path 13.

Further, since the flow deflectors 23 and 42 can reduce the flow colliding with the opening hole sealing portion 21, even if a fine powdery foreign material such as dust is contained in the fluid to be measured, the flow deflecting members 23 and 42 can be applied to the opening hole sealing portion 21. Foreign matter can be reduced. For this reason, the specification of the opening hole sealing portion 21 that allows the transmission of the ultrasonic wave is considered first, and the degree of freedom of selection or setting is improved, and the transmission of the ultrasonic wave is further increased, so that high sensitivity can be achieved. Low input or high accuracy can be realized.

Further, by providing the opening sealing portion 21 and the flow deflectors 23 and 42 in the opening 11 on the upstream side similarly to the opening 12 on the downstream side, the same effect can be obtained in the opening 11 and the reverse direction. The measurement accuracy can be further improved with respect to the flow of air, and the transmission of ultrasonic waves can be enhanced to achieve higher sensitivity, lower power consumption, or higher accuracy.

As described above, according to the third embodiment, even when an instantaneous reverse flow occurs due to a flow accompanied by pulsation, the flow of the fluid to be measured into the opening hole is reduced as in the case of the forward flow, and the ultrasonic transceiver is used. The turbulence of the flow between them can be greatly reduced, the measurement accuracy can be increased, and the upper limit value at which the flow rate can be measured can be increased. In addition, measurement can be performed with high accuracy even in the case of a reverse flow, so that the degree of freedom of installation is high and convenience can be improved.

In addition, the flow deflector is provided on the upstream and downstream sides of the opening to further improve the measurement accuracy and suppress the inflow into the opening and prevent the flow from flowing in the forward and backward directions of the measurement flow path. Foreign matter can be prevented from entering the hole, and stable measurement accuracy can be maintained for a long period of time even if a pulsating flow is accompanied by a reverse flow, so that durability and reliability can be improved.

In the third embodiment, the case where the bent portions 17 and 18 are bent in the direction of the width W of the measurement channel 6 is shown. However, the bending direction of the bent portions 17 and 18 is the direction of the height H of the measurement channel 6. Needless to say, the bending direction may be any direction, and the bending directions of the bent portion 17 and the bent portion 18 may be different.

(Example 4)
15, the same members and the same functions as those in the embodiment of FIGS. 1 to 14 are denoted by the same reference numerals, detailed description thereof will be omitted, and different portions will be mainly described.

Reference numeral 43 denotes a propagation path flow regulating member provided on the upstream side of the ultrasonic propagation path 13. The propagation path flow regulating body 43 is substantially parallel to the ultrasonic wave propagation path 13 obliquely crossing the measurement flow path 6. It is provided at a position slightly away from the ultrasonic wave propagation path 13 so as not to disturb the propagation of the ultrasonic wave.

FIG. 16 shows the propagation path flow restricting body 43 viewed from the flow direction of the measurement flow path 6, and the propagation path flow restriction body 43 is disposed in the measurement flow path 6 having a circular cross section. Reference numeral 13a denotes an ultrasonic wave propagation path shown in the cross section of the measurement flow path 6 along the paper surface direction (the height direction of the measurement flow path 6) in FIG. 15, and the propagation path flow restrictor 43 has a width in the height direction. Are provided in the height direction as compared with the ultrasonic wave propagation path 13a indicated by a two-dot chain line, and a plurality of regulating portions 44 are provided to be exposed in the flow.

Next, the operation of the ultrasonic flow measurement device will be described. The flow path of the measurement fluid 6 is changed while the flow of the fluid to be measured is increased or decreased by an on-off valve (not shown) provided on the upstream side of the measurement flow path 6 or flows through the bent portion 17. Turbulence is promoted by the regulating portion 44 of the propagation path flow regulating body 43 provided immediately before the upstream side of the ultrasonic wave propagation path 13.

Since the propagation path flow restricting body 43 is arranged immediately before the upstream side over the entire area of the ultrasonic propagation path 13 from a position near the upstream ultrasonic transmitter / receiver 8 to a position near the downstream ultrasonic transmitter / receiver 9, Turbulence is promoted uniformly over the entire area of the sound wave propagation path 13. As described above, the difference in the flow state in the ultrasonic wave propagation path 13 from the upstream side to the downstream side is reduced, so that the average flow velocity in the ultrasonic wave propagation path 13 can be easily measured.

In particular, even when the flow state is small (when the flow rate is small) and the flow state is laminar and flows into the measurement flow path 6, the flow state in the ultrasonic wave propagation path 13 is promoted to be turbulent by the propagation path flow restrictor 43. Is done. Therefore, a difference between the turbulent state and the turbulent state in the ultrasonic wave propagation path 13 when the flow velocity is large (when the flow rate is large) and flows into the measurement flow path 6 in a turbulent state is reduced.

Therefore, the flow in the ultrasonic wave propagation path 13 can be turbulently stabilized in a wide flow rate range from a small flow rate to a large flow rate. Further, since the propagation path flow restricting member 43 is disposed obliquely in the measurement flow path 6, the length in the measurement flow path 6 can be made longer than when the propagation path flow restriction body 43 is disposed orthogonal to the measurement flow path 6. Therefore, the propagation path flow restricting member 43 having a large aperture ratio is made possible, and a measuring device with reduced pressure loss can be realized.

In the measurement flow path 6 configured as described above, the flow velocity V is determined based on the propagation times T1 and T2 of the ultrasonic wave as described above, and the flow rate is determined from the cross-sectional area S of the measurement flow path 6 and the correction coefficient K. By the way, when the propagation path flow restricting body 43 along the ultrasonic wave propagation path 13 is not provided, the correction coefficient K greatly changes in a transition region where a transition is made from a laminar flow region to a turbulent flow region as shown in FIG. When an error ΔQm occurs in the measured flow rate, the correction coefficient greatly changes to ΔK1, and the flow rate measurement error is enlarged.

誤差 This error is caused by a change in the kinematic viscosity coefficient due to a change in the temperature of the fluid or a change in the composition ratio of the fluid, and is caused by a difference in flow state due to a difference in Reynolds number. In particular, when measuring the flow rate of city gas, LPG (liquefied petroleum gas), or the like, it is necessary to consider this when there is a possibility of a change in gas composition due to seasonal or regional differences.

However, when the propagation path flow restricting member 43 is installed along the ultrasonic propagation path 13 as in the present embodiment, the correction coefficient K is small even in the laminar flow region where the flow velocity is small as shown in FIG. Since the turbulence can be evenly distributed from the upstream side to the downstream side, the difference from the correction coefficient in the turbulence region where the flow velocity is large can be reduced, and the change in the correction coefficient is small even in the transition region where laminar flow shifts to turbulence The coefficients are flattened.

Accordingly, even if an error ΔQm occurs in the measured flow rate, the change in the correction coefficient can be made sufficiently small as ΔK2 (K2 <K1), and measurement with improved measurement accuracy can be performed. This is effective when there is a change in temperature or a change in the composition of the fluid. In particular, when measuring the flow rate of fuel gas such as city gas or LPG in which a change in composition and a change in temperature are considered, measurement with even higher accuracy can be realized.

Note that the propagation path flow restrictor 43 has an example in which the length from the entrance side 43a to the exit side 43b is substantially equal to the width W direction of the measurement flow path 6, but the propagation path flow restriction body shown in FIG. 43, as in the other embodiment, even if only the exit side 43b on the side of the ultrasonic wave propagation path 13 is along the ultrasonic wave propagation path 13 and the entrance side 43a is not along the ultrasonic wave propagation path 13, Since the turbulence is uniformly promoted in the sound wave propagation path 13 from the upstream side to the downstream side, it goes without saying that the length from the inlet side 43a to the outlet side 43b may be changed depending on the position in the width direction.

The propagation path flow restrictor 43 is disposed only in the ultrasonic propagation path 13 with respect to the circular cross section of the measurement flow path 6. However, the provision of the correction coefficient K Needless to say, flattening can be promoted. Further, in the present embodiment, the outlet side 43b of the propagation path flow restricting body 43 is disposed substantially parallel along the ultrasonic propagation path 13, but the upstream end to the downstream end of the ultrasonic propagation path 13 are arranged. Needless to say, it is only necessary to arrange the measurement flow path 6 at substantially equal positions in the width W direction, and there may be some irregularities on the outlet side 43b.

FIG. 20 is a configuration diagram of an ultrasonic flow measurement device showing another embodiment of the propagation path flow restricting member. 20, the same members and the same functions as those of the embodiment of FIGS. 1 to 19 are denoted by the same reference numerals, detailed description thereof will be omitted, and different portions will be mainly described.

Reference numeral 45 denotes a propagation path flow restrictor provided on the downstream side of the ultrasonic transmission path 13, and the downstream path flow restriction body 45 substantially extends along the ultrasonic transmission path 13 obliquely crossing the measurement flow path 6. They are arranged in parallel with each other and are provided slightly away from the ultrasonic wave propagation path 13 so as not to disturb the propagation of the ultrasonic wave. Reference numeral 46 denotes a regulating unit provided in the propagation path flow regulating body 45 to touch the flow of the measurement channel 6. Thus, the ultrasonic wave propagation path 13 is surrounded by the propagation path flow restricting body 43 on the upstream side and the propagation path flow restricting body 45 on the downstream side.

Next, the operation of the ultrasonic flow measurement device will be described. Due to the regulating portion 44 of the propagation path flow regulating member 43 provided immediately before the upstream side of the ultrasonic wave propagation path 13 over the entire area of the measurement flow path 6 in the width W direction, the flow uniformly flows over the entire area of the ultrasonic wave propagation path 13 in the width W direction. Is promoted.

Further, the propagation path flow restricting body 45 provided on the downstream side surrounds the ultrasonic propagation path 13 with the upstream side propagation path flow restricting body 43, so that a back pressure is applied to the flow in the ultrasonic propagation path 13 so that the flow state is reduced. And the flattening of the correction coefficient can be realized, and the ultrasonic wave propagation path 13 due to the pulsation due to the difference in the pipe shape on the downstream side of the measurement flow path 6 or the use condition of the fluid to be measured. It is possible to measure the flow rate stably by reducing the influence of the flow state in the inside, and to maintain the flattening of the correction coefficient even when the backflow occurs, thereby improving the measurement accuracy.

FIG. 21 is a perspective view of a propagation path flow restricting body 47 in which an upstream propagation path flow restricting body 43 and a downstream propagation path flow restricting body 45 are integrated. A connecting portion which connects and integrates with the downstream propagation path flow restricting body 45, and 49 is an ultrasonic wave propagation window having a perforated structure so as not to hinder ultrasonic wave propagation.

The propagation path flow restricting members 47 are connected to each other by a connecting portion 48 and integrated to prevent the upstream and downstream restricting portions 44 and 46 from being displaced from each other. Variation can be reduced and stabilized, and measurement with small variation can be realized. In addition, the propagation path flow restricting body 47 can increase the structural strength by the connecting portion 48, and each of the propagation path flow restricting bodies 43 and 45 can be thinned or miniaturized including the restricting sections 44 and 46. The flow state in the ultrasonic wave propagation path 13 can be equalized regardless of the cross-sectional position of the measurement flow path 6.

{Circle around (4)} The thickness of the regulating portions 44 and 46 is reduced or reduced, so that the opening area for the flow of the fluid to be measured can be increased, so that the pressure loss in the measurement flow path can be reduced. In addition, since the propagation path flow restrictors 43 and 45 are reinforced by the connecting portions 48, they can be prevented from being deformed over a long period of use, thereby improving durability and reliability.

Although the connecting portion 48 is shown to be installed at the corner of the propagation path flow restricting body 47, the connecting portion 48 can be provided at any position suitable for reinforcement as long as it does not interfere with the propagation of ultrasonic waves. Needless to say.

FIG. 22 is an AA cross-sectional view showing another cross-sectional shape of the measurement flow channel 6 according to the fourth embodiment. Reference numeral 50 denotes a flow channel wall in which the cross-sectional shape of the measurement flow channel 6 is rectangular having a width W and a height H. The restricting portions 44 and 46 are arranged in the entire rectangular cross section.

Next, the measurement operation in this rectangular section will be described. The ultrasonic wave propagation path 13 traverses the entire width W direction of the rectangular cross section, and can increase the ratio of the measurement area with respect to the height H direction of the rectangular cross section, and extends over the entire width W direction from the upstream side to the downstream side. Since the ratio of the measurement area in the height H direction can be made the same, highly accurate measurement of the average flow velocity of the fluid in the ultrasonic wave propagation path 13 becomes possible.

Further, the flow in the ultrasonic wave propagation path 13 is uniformly promoted from the upstream side to the downstream side in a wide flow rate region by the regulating portions 44 and 46 of the propagation path flow regulating members 43 and 45, and the average flow velocity is accurately measured. it can. For this reason, it is not necessary to increase the aspect ratio (W / H) of the rectangular cross section to increase the flatness and generate a stable two-dimensional flow in the measurement flow path 6, thereby increasing the measurement accuracy. The height H may be set from the viewpoint of reducing the influence of ultrasonic reflected waves on the upper and lower surfaces forming the height H of the cross section.

Therefore, the cross-sectional specification can be freely set to the flow path height H for reducing the interference of the reflected wave, and the transmission and reception of the ultrasonic wave with increased sensitivity can be performed. In addition, the measurement accuracy can be improved by reducing the fluctuation of the correction coefficient.

Furthermore, the pressure loss of the measurement flow path can be reduced as a cross section in which the length of contact with the fluid to be measured is reduced as a rectangular cross section having a small flatness whose aspect ratio is smaller than 2 in the cross section. In addition, in order to ensure the durability of production equipment such as a mold, as in the case where the fluid passage wall 7 is formed by die casting or the like, a substantially rectangular shape having rounded corners (corners R) in a rectangular cross section is also used. Needless to say, it is included in the rectangular cross section.

FIG. 23 shows the installation distance of the propagation path flow restricting body 43 or 45 from the ultrasonic wave propagation path 13 in this embodiment. The upstream propagation path flow restriction body 43 sets the distance from the ultrasonic wave propagation path 13 to Gu. The distance from the ultrasonic wave propagation path 13 of the propagation path flow regulating body 45 on the downstream side is Gd.

Here, the installation distance between the propagation path flow restrictors 43 and 45 and the ultrasonic wave propagation path 13 is optimized so that the correction coefficient of the measurement value can be flattened in a wide flow rate range for various fluids to be measured. The flow distribution in the propagation path 13 is uniformly turbulent from the upstream side to the downstream side. For example, when the Reynolds number is small, the distances Gu and Gd can be reduced, and when the Reynolds number is large, the distances Gu and Gd can be increased. Since the Reynolds number is proportional to the reciprocal of the kinematic viscosity coefficient, the distances Gu and Gd can be increased for a fluid having a small viscosity, and the distances Gu and Gd are decreased for a fluid having a large viscosity.

For example, the kinematic viscosity coefficient of propane gas is 4.5 mm ² / s (300 ° K), and the kinematic viscosity coefficient of methane gas is 17.1 mm ² / s (300 ° K). Gu and Gd can be increased, and in the case of methane gas, the distances Gu and Gd are reduced. Under these conditions, in order to reduce the influence of the ultrasonic wave propagating in the ultrasonic wave propagation path 13 reflected on the propagation path flow regulating bodies 43 and 45 and affecting the flow velocity measurement, the propagation path flow regulating bodies 43 and 45 are The distance from the ultrasonic wave propagation path 13 should be set as large as possible. However, since the flow is uniformly turbulent from the upstream side to the downstream side in the ultrasonic wave propagation path 13, the installation distance is optimized. Is required.

Further, the distances Gu and Gd do not need to be the same and may be set to different values, and the shape of the regulating portions 44 and 46 of the upstream or downstream propagation path flow regulating members 43 and 45 and the fineness of the opening size may be set. It goes without saying that the magnitude relationship between the distances Gu and Gd is different due to differences in length and the like.
When the shapes and opening dimensions of the regulating portions 44 and 46 are changed depending on the type of fluid, it goes without saying that the relationship between the installation distance and the viscosity may be different from the above.

Therefore, the shape and dimensions of the measurement flow path 6 can be made the same, and high-precision measurement can be performed for various fluids by simply changing the flow path flow restricting body, and the convenience for the user can be improved. The measurement device can be provided at low cost by sharing various members.

FIG. 24 is a perspective view showing another embodiment of the propagation path flow restricting body. Reference numeral 51 denotes a restricting portion of the propagation path flow restricting body 43. The restricting section 51 has a wire mesh, a woven fabric, or the like having a small thickness in the flow direction. It is formed of a mesh. It is also possible to provide a similar regulating portion 51 (not shown) for the downstream-side propagation path flow regulating member 45. It goes without saying that the outer periphery frame 44a of the propagation path flow restricting body can be eliminated and the propagation path flow restricting body can be formed only by the mesh body.

Here, since the regulating part 51 is formed of a net having a small thickness in the flow direction, the propagation path flow restrictor 43 or 45 can be made small in the flow direction, and can be installed in a small space. Can be downsized. In addition, if the mesh surrounding the ultrasonic wave propagation path 13 is made of a material that does not easily reflect the ultrasonic waves, the reflection of the ultrasonic waves by the propagation path flow restricting body 43 or 45 can be achieved in addition to the shape effect of the mesh having a large aperture ratio. It is possible to realize high-precision measurement by reducing the influence on the measurement accuracy deterioration due to the interference of the reflected wave.

FIG. 25 is a perspective view showing another embodiment of the propagation path flow restricting body. Reference numeral 52 denotes a restricting portion of the propagation path flow restricting body 43. The restricting section 52 has a large number of wall surfaces 52a in the flow direction. The body 53 is constituted. It is also possible to provide a similar regulating portion 52 (not shown) for the downstream propagation path flow regulating body 45.

The flow direction passing through the propagation path flow restrictor 43 can be restricted by the wall surface 52a provided in the flow direction, and in particular, the flow of the flow into the opening holes 11 and 12 immediately before the ultrasonic transceivers 8 and 9 is reduced. As a result, the generation of vortices is reduced, and the attenuation of ultrasonic waves due to vortices is reduced, so that measurement can be performed up to a larger flow rate region. In addition, by deflecting each wall surface 52a in a direction that makes the flow velocity distribution in the ultrasonic wave propagation path 13 more uniform, the flow velocity distribution in the ultrasonic wave propagation path 13 can be made even more uniform, and the measurement accuracy is improved. it can.

FIG. 26 is a front view of another embodiment of the propagation path flow restrictor viewed from the flow direction, and reference numeral 54 denotes two adjacent restrictions provided on the propagation path flow restrictor 43 depending on the position of the cross section of the measurement flow path 6. This is a regulating portion in which the cross-sectional area of the passage hole 55 is changed by changing the interval between the portions. Here, the cross-sectional area of the peripheral through-hole 55a is larger than the cross-sectional area of the central through-hole 55b of the propagation path flow restrictor 43. That is, the cross-sectional area of the passage hole 55 is increased on the end side in the width W direction or the end side in the height H direction of the propagation path flow restrictor 43. It is also possible to provide a similar regulating portion 54 (not shown) for the downstream propagation path flow regulating body 45.

Next, the operation will be described. If the propagation path flow restricting member 43 is not provided, the flow velocity decreases due to the viscosity of the fluid flowing along the wall of the measurement flow path 6 and the flow velocity in the central portion of the measurement flow path 6 becomes relatively high, so that a uniform flow velocity distribution is obtained. hard. However, here, the propagation path flow restricting body 43 is provided, and at the center of the cross section of the measurement flow path 6, the cross sectional area of the through hole 55 is reduced to reduce the flow velocity, and at the end side, the cross sectional area of the through hole 55 is increased. The flow resistance distribution in the ultrasonic wave propagation path 13 is equalized by reducing the passage resistance as compared with the central part to reduce the decrease in the flow velocity.

For this reason, the flow velocity in the ultrasonic wave propagation path 13 obliquely crossing the measurement flow path 6 is equalized from the upstream side to the downstream side, and the measured value of the average flow velocity in the ultrasonic wave propagation path 13 is orthogonal to the cross section of the measurement flow path 6. And the average flow velocity can be made to match well in a wide flow area from a laminar flow area to a turbulent flow area, and the change in the flow coefficient can be flattened to improve the measurement accuracy.

As described above, according to the fourth embodiment, the entire area of the ultrasonic wave propagation path 13 is controlled by the propagation path flow restrictor 43 provided immediately upstream in the entire area from the upstream end to the downstream end of the ultrasonic wave propagation path 13. , The turbulence is promoted, the flow rate change characteristic of the correction coefficient is flattened over the entire flow rate measurement range, and the measurement accuracy can be improved. Further, even if a change in the physical property value of the fluid occurs, the measurement accuracy is maintained, and the practicality and convenience can be improved.

伝 搬 Furthermore, by disposing the propagation path flow restricting member 43 obliquely in the measurement flow path 6, the aperture ratio can be increased, and a measuring device with reduced pressure loss can be realized. In addition, since the propagation path flow restricting body 43 is obliquely disposed in the measurement flow path 6, a large area of a portion where the restricting section 44 is provided can be ensured. Therefore, the distance between the restricting sections 44 can be reduced without increasing the pressure loss. By providing a large number, the turbulence promoting effect can be enhanced.

In addition, the ultrasonic wave propagation path 13 is surrounded by the propagation path flow restrictors 43 and 45 arranged on the upstream side and the downstream side, and the turbulence state in the ultrasonic wave propagation path 13 is corrected by equalizing from the upstream side to the downstream side. The coefficient can be further flattened, and the measurement accuracy can be further improved.

Further, the influence of the flow state on the downstream side of the measurement flow path 6 is reduced by the downstream propagation path flow restricting body 45, and stable measurement is realized regardless of the pipe state on the downstream side of the measurement flow path 6. The degree of freedom of installation of the measuring device can be improved. Further, the same effect can be obtained for either forward or backward flow in the measurement flow path, and the change in the correction coefficient can be flattened even during a pulsating flow or a backward flow, and the measurement accuracy can be improved.

In addition, by integrating the upstream and downstream propagation path flow restrictors 43 and 45, the installation distance between the propagation path flow restrictors or the mutual position of the upstream and downstream restriction sections is prevented from shifting and stabilized. Thus, a measuring device with less variation can be realized. Further, since the propagation path flow regulating body is reinforced by the connection section, the regulation section can be made finer or thinner, and the flow state in the ultrasonic propagation path can be equalized or the pressure loss in the measurement flow path can be reduced. .

Further, regardless of the type of the fluid to be measured, the measurement flow path can be shared and the convenience can be improved only by changing the installation distance of the propagation path flow restrictor from the ultrasonic wave propagation path 13, and regardless of the type of the fluid to be measured. And stable measurement accuracy can be maintained. Further, the cost can be reduced by sharing the measurement flow path.

In some cases, the regulating portion may be formed of a net-like body, so that the installation space for the propagation path flow regulating body can be made thinner and smaller in the flow direction, and the measurement flow path can be made smaller.

The restricting portion may be formed of a lattice body, and the flow direction in the ultrasonic wave propagation path is further uniformed by restricting the flow direction by the wall surface extending in the flow direction, so that the measurement accuracy can be improved.

Further, the mutual interval between two adjacent regulating portions may be changed according to the cross-sectional position of the measurement channel, and the size of the opening in each of the regulating portions is reduced while the length in the flow direction is kept small. By optimizing the position of the cross section, the flow velocity distribution in the ultrasonic wave propagation path can be further equalized, and the length of the regulating section in the flow direction can be reduced, so that pressure loss is reduced and measurement accuracy is improved by equalizing the flow velocity distribution. Improvement can be compatible.

In addition, by making the measurement flow channel a rectangular cross-section, the ratio of the measurement area in the measurement cross-section can be increased, and the flow can be measured under the same conditions from the upstream side to the downstream side of the ultrasonic wave propagation path. Can be measured.

In addition, the rectangular cross-section of the propagation path flow restrictor and measurement channel arranged along the ultrasonic propagation path frees the section from having a high aspect ratio for causing a two-dimensional flow, and the section specification of the reflected wave The height of the flow path can be set freely to reduce interference, and transmission and reception of ultrasonic waves with increased sensitivity can be performed. Further, the pressure loss of the measurement flow path can be reduced as a cross section in which the length of contact with the fluid is reduced without excessively flattening the measurement cross section.

In the present embodiment, the case where the bent portions 17 and 18 are bent in the direction of the width W of the measurement flow channel 6 is shown. However, the bending direction of the bent portions 17 and 18 is the same in the direction of the height H of the measurement flow channel 6. It goes without saying that the bending direction may be any direction as well as the bending direction of the bent portion 17 and the bent portion 18 may be different.

(Example 5)
27, the same members and the same functions as those in the embodiment of FIGS. 1 to 26 are denoted by the same reference numerals, detailed description is omitted, and different portions will be mainly described.

Reference numeral 56 denotes an inflow suppressor that reduces the flow of the fluid to be measured into the opening holes 11 and 12, and is provided on the downstream side of the propagation path flow regulating body 43 provided on the upstream side of the ultrasonic wave propagation path 13. The inflow restricting body 56 includes a first inflow restricting body 57 composed of an open hole sealing portion 21 having a number of ultrasonic passage openings 22 through which ultrasonic waves can pass as shown in an enlarged view in FIG. The stop portion 21 traverses the ultrasonic wave propagation path 13 and is provided flush with the measurement flow path surface 6a of the opening holes 11 and 12 to reduce the flow into the opening holes 11 and 12.

FIG. 29 shows another embodiment of the inflow suppressor, in which a flow deflector 58a arranged near the upstream of the upstream opening hole 11 so as to protrude from the flow path wall 7 and the flow deflector 58a The flow near the measurement flow path surface 6a is deflected by the first inflow suppressing body 58 formed by the guide surface 58b provided on the upstream side and having a smoothly increased height, and flows into the opening hole 11 so as to be kept away from the wall surface. I try not to. When the installation distance Gu or Gd of the propagation path flow restricting body from the ultrasonic wave propagation path is small, the flow deflector 58a and the guide surface 58b are formed integrally with the propagation path flow restricting body 43 to form the second inflow suppressing body. It is possible.

In FIG. 30, reference numeral 60 denotes a second inflow restricting body in which a flow deflector 60 a is provided on the measurement flow path wall 6 a side of the propagation path flow restricting body 59 to form an inflow suppressing section 60 b. The second inflow suppressing body 60 is integrated.

Next, the flow state of the fluid to be measured in the ultrasonic flow measurement device will be described. First, the flow rate of the measurement fluid is changed while the flow of the fluid to be measured is increased or decreased by an on-off valve (not shown) provided on the upstream side of the measurement flow path 6 or flows through the bent portion 17. The turbulence is promoted by the regulating portion 44 of the propagation path flow regulating body 43 provided immediately before the ultrasonic wave propagation path 13 after entering the path 6.

Since the propagation path flow restricting body 43 is arranged immediately before the upstream side over the entire area of the ultrasonic propagation path 13 from a position near the upstream ultrasonic transmitter / receiver 8 to a position near the downstream ultrasonic transmitter / receiver 9, Turbulence is promoted uniformly over the entire area of the sound wave propagation path 13. As described above, the difference in the flow state in the ultrasonic wave propagation path 13 from the upstream side to the downstream side is reduced, so that the average flow velocity in the ultrasonic wave propagation path 13 can be easily measured. In particular, even when the flow state is small (when the flow rate is small) and the flow state is laminar and flows into the measurement flow path 6, the flow state in the ultrasonic wave propagation path 13 is promoted to be turbulent by the propagation path flow restrictor 43. Is done.

Therefore, the difference between the turbulent state and the turbulent state in the ultrasonic wave propagation path 13 when the flow velocity is large (when the flow rate is large) and flows into the measurement flow path 6 in a turbulent state is reduced. Accordingly, the flow in the ultrasonic wave propagation path 13 can be made turbulent in a wide flow rate range from a small flow rate to a large flow rate. Further, since the propagation path flow restricting member 43 is disposed obliquely in the measurement flow path 6, the length in the measurement flow path 6 can be made longer than when the propagation path flow restriction body 43 is disposed orthogonal to the measurement flow path 6. Therefore, the propagation path flow restricting body 43 having a large opening area is made possible, and a measuring device with reduced pressure loss can be realized.

Next, the flow near the opening hole will be described. First, when only the first inflow suppressing body 57 or 58 provided in the downstream opening hole 12 is used as the inflow suppressing body, the downstream side where a stronger vortex is likely to be generated because it intersects the flow at an acute angle. By reducing the flow into the opening hole, the turbulence of the flow between the ultrasonic transceivers can be efficiently reduced, and the upper limit value at which the flow rate can be measured can be increased. In particular, in the case where the opening hole sealing portion 21 is the first inflow suppressing body 57, the inflow suppressing effect can be further enhanced to reduce the flow in the opening holes, and the opening holes are sealed in both the opening holes 11 and 12. The amount of attenuation of the ultrasonic wave can be reduced as compared with the case where the unit 21 is provided, and the driving input to the ultrasonic transceiver can be reduced to realize low power consumption.

Next, when the inflow suppressing body is the first inflow suppressing body 57 or 58 provided in the opening holes 11 and 12 on both the upstream side and the downstream side, the flow in the ultrasonic wave propagation path is large. Disturbance in the opening hole, which accounts for the ratio, can be efficiently reduced, and the measurement accuracy and the upper limit of the flow rate that can be measured can be increased.

Particularly, in the case where the opening hole sealing portion 21 is the first inflow suppressing body 57, the turbulence of the flow can be efficiently reduced with respect to either the forward flow or the reverse flow in the measurement flow path. A first inflow suppressing member 58 including a flow deflector 58a is provided in the upstream opening hole 11, and a first inflow suppressing member 57 including the opening hole sealing portion 21 is provided in the downstream opening hole 12. In this case, it is needless to say that the power consumption of the ultrasonic transceiver can be reduced by further reducing the turbulence of the flow between the ultrasonic transceivers and reducing the attenuation of the ultrasonic waves.

Further, when the inflow suppressing body is provided with an inflow suppressing portion in the propagation path flow restricting body to serve as the second inflow suppressing body, the inflow into the opening hole is suppressed and the propagation path flow restricting body and the inflow suppressing body are integrated. Accordingly, it is possible to reduce the variation of the characteristic of suppressing the inflow into the opening hole, thereby improving the reliability, and to form a compact ultrasonic propagation path, so that the measurement flow path can be downsized.

Ultrasonic waves are transmitted and received between the ultrasonic transceivers 8 and 9 with respect to the ultrasonic wave propagation path 13 in which the flow is stabilized in this way, so that highly accurate flow velocity measurement can be realized, and the attenuation of the ultrasonic waves due to the fluctuation of the flow can be reduced. It is possible to increase the upper limit of the flow rate that can be measured by reducing the flow rate.

If the first inflow suppressors 57 and 58 or the second inflow suppressor 60 is not provided, the downstream opening hole 12 intersects the measurement flow path 6 at an acute angle, so that a strong flow in the measurement flow path 6 is generated. A strong vortex is generated by flowing into the opening hole 12, and the accuracy of flow velocity measurement is reduced due to partial flow velocity fluctuation, and the upper limit of the measurable flow rate is reduced due to attenuation of ultrasonic waves due to the vortex.

In addition, even if the first inflow suppressing members 57 and 58 or the second inflow suppressing member 60 is not provided in the upstream opening hole 11, the flow inflow occurs, but the opening hole 11 forms an obtuse angle with respect to the measurement flow path 6. Vortices, the intensity of the vortex is smaller than in the case of the downstream opening hole 12, and its adverse effect is small. However, it is needless to say that the flow is further stabilized by providing the first inflow suppressing bodies 57 and 58 or the second inflow suppressing body 60 in the opening 11 on the upstream side.

Next, the correction coefficient K for obtaining the flow rate based on the ultrasonic propagation times T1 and T2 will be described. The turbulence is promoted in the entire area of the ultrasonic wave propagation path 13 by the propagation path flow restrictor 43 provided immediately upstream in the entire area from the upstream end to the downstream end of the ultrasonic wave propagation path 13. As shown in FIGS. 17 and 18, K has a small change with respect to the flow rate change and becomes flat, and the flatness of the flow rate change characteristic of the correction coefficient maintains the measurement accuracy even if the fluid property value changes. The efficiency and convenience can be improved, and the turbulence of the flow between the ultrasonic transceivers can be greatly reduced, so that the reception level of the ultrasonic wave can be increased in the entire range of the measurement range, and the measurement accuracy can be further improved.

Moreover, the flow into the openings 11 and 12 can be reduced to greatly reduce the turbulence of the flow between the ultrasonic transceivers, and the upper limit of the flow rate can be increased. Also, when the opening hole sealing part is a mesh of inclined mesh that is inclined with respect to the horizontal, or when the flow deflector is provided on both the upstream side and the downstream side of the opening hole, the flow coefficient is flattened and measured. The accuracy can be improved, and the effects described above in the first embodiment are added, so that the reliability can be further improved.

FIG. 31 shows another embodiment of the inflow suppressing body, in which the first inflow suppressing body 57 including the opening hole sealing portion 21 having the ultrasonic wave passage 22 and the measurement flow path surface of the propagation path flow restricting body 61 are shown. It is provided as a second inflow suppressing body 62 including an inflow suppressing portion 62a provided on the 6a side. Therefore, the measurement accuracy can be further improved by further increasing the effect of suppressing the inflow of the fluid to be measured into the opening hole, and the adhesion of foreign substances such as dust to the sealing portion of the opening hole can be reduced by the flow deflector. Therefore, it is possible to select the sealing part of the opening hole with higher flexibility, placing priority on the ultrasonic wave transmission without giving priority to clogging. An apparatus with excellent measurement accuracy can be realized.

Further, since the second inflow suppressing body 62 can be processed as a part of the propagation path flow regulating body 61 into a shape suitable for the flow rate or the physical property value of the fluid to be measured, the measurement flow path 6 itself can be easily shared. become. Furthermore, measurement accuracy and reliability are reduced by reducing the turbulence in the opening hole due to the synergistic effect of the first and second inflow suppression bodies and reducing the variation in the inflow suppression characteristics into the opening hole by integrating the propagation path flow control body and the inflow suppression body. Performance can be enhanced, and a compact ultrasonic propagation path can be formed, so that the measurement channel can be downsized.

FIGS. 32 and 33 show another embodiment of the propagation path flow restricting body and the inflow suppressing body. The upstream propagation path flow restricting body 43 and the downstream side propagation path flow restricting body 45 form an ultrasonic wave propagation path. 13 and an inflow suppressor 56 is provided. As shown in FIG. 33, these propagation path flow restrictors 43 and 45 are connected and integrated by a connecting portion 48, and an inflow suppressing member 56 is attached to the ultrasonic wave propagation window 49. The inflow suppressing body 56 is a mesh as the opening hole sealing portion 21 that covers the opening holes 11 and 12.

In this configuration, the flow in the ultrasonic wave propagation path 13 is uniformed and stabilized because the back pressure is applied by the propagation path flow regulating body 45 on the downstream side. It is possible to reduce the influence of the flow state in the ultrasonic wave propagation path 13 due to a difference or a pulsation due to the use condition of the fluid to be measured, and to perform a stable flow rate measurement.

Further, since the inflow suppressing members 56 are provided in the opening holes 11 and 12, the upper limit of the measurable flow rate can be increased.

In addition, since the propagation path flow restricting bodies 43 and 45 are connected to each other and the opening sealing portion 21 as the inflow suppressing body 56 is integrated, the positional relationship such as mutual distance is determined and the flow state is stabilized. Thus, variations in the flow state in the ultrasonic wave propagation path 13 can be reduced, and stable measurement with small variations can be realized. In addition, by integrating not only the propagation path flow restrictors 43 and 45, but also the opening hole sealing portion 21, the strength of the propagation path flow restriction body can be further reinforced, and the deformation can be prevented over a long period of use and the durability can be reduced. Performance and reliability can be improved.

The propagation path flow restrictor 43 is disposed substantially parallel to the width W direction of the measurement flow path 6 along the ultrasonic wave propagation path 13, but is not illustrated in the height H direction of the measurement flow path 6. As described with reference to FIG. 16, the cross section may be arranged in the measurement flow channel 6 having a circular cross section, and as described with reference to FIG. The effect in can be expected similarly.

In addition, the opening shape of the opening hole may be a shape having one side in a direction substantially orthogonal to the flow direction of the measurement flow path, or a non-uniform flow suppressing body may be arranged at an upstream introduction portion or a downstream extraction portion of the measurement flow path. The same effect can be expected in the above-described embodiment also in the case where the operation is performed.

As described above, according to the fifth embodiment, the entirety of the ultrasonic wave propagation path 13 is controlled by the propagation path flow restrictor 43 provided immediately upstream in the entire area from the upstream end to the downstream end of the ultrasonic wave propagation path 13. The turbulence is promoted in the flow rate, and the flow rate change characteristics of the correction coefficient are flattened over the entire flow rate measurement range to prevent the expansion of the error due to the correction coefficient, thereby improving the measurement accuracy. Therefore, the disturbance of the flow in the ultrasonic wave propagation path can be greatly reduced by reducing the inflow of the ultrasonic wave, so that the reception level of the ultrasonic wave can be increased and the upper limit value at which the flow rate can be measured can be increased.

In addition, the inflow suppressing body is disposed as a first inflow suppressing body provided in the downstream opening hole, and the inflow suppressing body is disposed in the downstream opening hole where a stronger vortex is easily generated because it intersects the flow at an acute angle. By reducing the flow into the opening hole, the turbulence of the flow between the ultrasonic transceivers can be efficiently reduced, and the upper limit value at which the flow rate can be measured can be increased.

In addition, the inflow suppression body is a first inflow suppression body provided in the upstream and downstream opening holes, and measures the turbulence in the opening hole which accounts for a large proportion of the flow disturbance in the ultrasonic wave propagation path. , The flow can be efficiently reduced for either forward or reverse flow, and the measurement accuracy and the upper limit of the flow rate can be increased.

In addition, the inflow suppressing body is provided with an inflow suppressing portion in the propagation path flow regulating body, and as a second inflow suppressing body, the dispersion of the inflow suppressing characteristics to the opening hole is reduced by integrating the propagation path flow regulating body and the inflow suppressing body. Therefore, the reliability can be improved, and a compact ultrasonic propagation path can be formed, so that the measurement flow path can be downsized.

Further, the first inflow suppressing body is an opening hole sealing portion having at least one ultrasonic transmission port, and the opening hole is covered with the opening hole sealing portion to further suppress the inflow of the fluid to be measured into the opening hole. By increasing the flow, the flow in the opening can be reduced and stabilized, and the propagation of ultrasonic waves can be ensured by the ultrasonic passage, and the ultrasonic attenuation when the opening sealing part is placed only in the downstream opening And the drive input to the ultrasonic transceiver can be reduced to achieve low power consumption.

Further, the first inflow suppressing body includes an opening hole sealing portion having at least one ultrasonic transmission port and a flow deflector provided in the vicinity of the opening hole, and has an effect of suppressing the inflow of the fluid to be measured into the opening hole. In addition, by further increasing the measurement accuracy, measurement accuracy can be further improved, and foreign matter such as dust can be reduced from adhering to the opening hole sealing portion by the flow deflector, so that the opening hole sealing portion does not place importance on clogging. It is possible to select a device with a high degree of freedom, with the ultrasonic wave permeability being the first priority, and to realize a device with lower input or higher sensitivity and higher measurement accuracy by further increasing the ultrasonic wave permeability.

Further, the inflow suppressing body is provided with a first inflow suppressing body provided in the opening hole and a second inflow suppressing body provided in the propagation path flow restricting body, and the opening due to a synergistic effect of the first and second inflow suppressing bodies. The measurement accuracy and reliability can be improved by reducing the turbulence in the hole and the dispersion of the inflow suppression characteristics into the opening hole by integrating the propagation path flow control body and the inflow suppression body, and a compact ultrasonic wave propagation path is formed. Therefore, the measurement channel can be downsized.

In the present embodiment, the case where the bent portions 17 and 18 are bent in the direction of the width W of the measurement flow channel 6 is shown. However, the bending direction of the bent portions 17 and 18 is the same in the direction of the height H of the measurement flow channel 6. It goes without saying that the bending direction may be any direction as well as the bending direction of the bent portion 17 and the bent portion 18 may be different.

(Example 6)
34, the same members and the same functions as those in the embodiment of FIGS. 1 to 33 are denoted by the same reference numerals, detailed description thereof will be omitted, and different portions will be mainly described.

# 63 is a plurality of divided passages provided in the opening holes 11 and 12 and dividing the opening holes 11 and 12 in the ultrasonic wave propagation direction. As shown in FIG. 35, the divided passage 63 has an inlet surface 65 along the vibration surface 64 of the ultrasonic transceiver 9 and an outlet surface 66 along the measurement flow passage surface 6a. One side 67 of the cross section has a dimension longer than a half wavelength λ / 2 of the ultrasonic wave used for transmission and reception, and a dimension that is not an integral multiple of the half wavelength of the ultrasonic wave.

{Circle around (2)} The distance 68 between the divided passage 63 in the opening 12 and the vibration surface of the ultrasonic receiving / oscillating element 9 is an integral multiple of the half wavelength λ / 2 of the ultrasonic wave. Then, the thickness d of the partition forming the divided passage 63 is set to a dimension shorter than the wavelength λ of the ultrasonic wave. Here, only the ultrasonic transmitter / receiver 9 on the downstream side has been described, but the same applies to the ultrasonic transmitter / receiver 8 on the upstream side.

Further, as shown in FIG. 36, each of the divided passages 63 of the opening 11 provided on the measurement flow path surface 6a on the side facing the ultrasonic transmitter / receiver 9 corresponds to one of the divided passages 63 of the other opening 12. They were arranged so as to extend on the same straight line as the two.

(5) Next, a general method of flow rate measurement will be described. As described above, the ultrasonic flow meter obtains the flow velocity V from the reciprocal difference between the propagation times T1 and T2 of the ultrasonic wave according to the following formula, and converts the flow velocity V into a flow rate by multiplying the cross-sectional area of the flow path. That is, the flow velocity V is obtained by the following equation.

V = [L / (2 cos θ)] × [(1 / T1) − (1 / T2)]
At this time, the propagation distance L of the ultrasonic wave affected by the flow differs depending on whether the flow enters the opening hole or not. That is, since the flow does not enter the opening hole depending on the flow velocity or the presence or absence of the pulsating flow, the effective propagation distance L changes and an error occurs in the measured flow rate.

ADVANTAGE OF THE INVENTION According to the structure of this invention, the inside of the opening hole provided in the measurement flow path is divided small, and it becomes difficult to generate a vortex. The inflow can be reduced, and even if the flow velocity changes or pulsation occurs, the effective propagation distance L can be kept constant, and the flow rate can be measured correctly. Since the ultrasonic wave propagates through the fluid to be measured in the divided passage, the sensitivity is less reduced than that of the bulk element, and the straightness of the ultrasonic wave is maintained by dividing the passage, so that good transmission and reception can be performed. .

Furthermore, the ultrasonic wave is perpendicularly incident on the divided passage, can travel straight along the divided passage, and can be a propagation path with no reflection or the like and with little attenuation. The exit is flat with respect to the measurement flow path surface, so that the flow of the boundary layer of the measurement flow path surface is not disturbed, and the ultrasonic waves can be efficiently emitted by aligning the exit surface as the radiation surface. Since the transmitting surface and the receiving surface of the pair of divided passages coincide with each other with respect to the traveling direction of the ultrasonic waves, it is possible to prevent the reflection and attenuation by the partition plates of the opposed opening holes.

の 一 Further, since one side 67 of the vertical cross section of the divided passage is longer than a half wavelength, the propagation path is less affected by the viscosity from the divided surface and has less attenuation. Furthermore, by setting the length of one side 67 not to be an integral multiple of the wavelength, it is possible to suppress the resonance in the lateral direction, and it is possible to propagate the light efficiently.

(4) By resonating the distance 68 between the ultrasonic transceiver and the entrance surface of the split passage with a length of a half wavelength, radiation can be performed efficiently. By making the thickness d of the partition of the divided passage shorter than the wavelength, the reflection of the ultrasonic wave when entering the divided passage can be prevented, and the ultrasonic wave can be efficiently propagated to realize good transmission and reception.

Here, the same effect can be exerted even in a rectangular divided passage section as shown in FIGS. 37, 38 and 39, and in a honeycomb-shaped divided passage as shown in FIG. In addition, the thickness d of the partition of the divided passage 63 can be made sufficiently smaller than the wavelength of the ultrasonic wave, and the opening hole can be divided vertically and horizontally. Then, the ultrasonic waves can be efficiently propagated, and good transmission and reception can be realized.

分割 One of the divided passages has an opening at the center of the opening. And since there is an opening in the center of the opening hole, it is aligned with the center axis of the ultrasonic transmitter / receiver, and efficiently propagates the central part where the output of ultrasonic waves is strong, and improves the signal transmission by ultrasonic transmission / reception. It is.

(4) In a polygon or the like in which the opposing surfaces of the divided passages are not parallel, the propagation perpendicular to the traveling direction of the ultrasonic waves is dispersed and resonance is unlikely to occur, and the ultrasonic waves are efficiently propagated. In particular, the honeycomb lattice material is used as a divided passage, and an opening is provided in the center to reduce the above-mentioned resonance phenomenon, the effect of the sufficiently thin partition thickness d, and the high-efficiency ultrasonic wave at the center where the ultrasonic output is strong. , The efficiency of signal transmission by ultrasonic transmission / reception can be further enhanced.

Furthermore, as shown in FIG. 41, the provision of the communicating portion 69 in the middle of the divided passages allows the passages to communicate with each other, thereby reducing the number of partition surfaces and minimizing the attenuation due to the wall surfaces. By making the size of the communication portion 69 longer than the wavelength of the ultrasonic wave, the divided passages can be easily connected. By providing the connecting portion and the partition portion alternately, it is possible to provide a partition effect and an effect of reducing attenuation.

Next, another embodiment of the divided passage will be described with reference to FIGS. FIG. 42 is a sectional view showing a divided passage 70 of the opening hole 12. The difference from the above-described embodiment is that the wire length Lb of the divided passage is shorter than the wavelength λ of the ultrasonic wave used for transmission and reception, and the wire mesh as the net material is arranged in a direction perpendicular to the ultrasonic wave propagation direction. That is, a divided passage is configured by arranging on the side of the ultrasonic transmitting / receiving element and on the side of the flow path along the wall of the flow path. FIG. 43 shows the opening 71.

(4) By making the path length shorter than the wavelength of the ultrasonic wave, the split path can be made a propagation path with less attenuation. In addition, the opening space inside the opening hole provided on the measurement flow path surface is divided into small portions, making it difficult for vortices to occur, and also reducing the flow of fluid into the opening hole, changing the flow velocity and reducing pulsation. Even if it occurs, the flow rate can be measured correctly. Since the ultrasonic wave propagates in the air in the divided passage, the sensitivity is less reduced than that of the bulk element, and the straightness of the ultrasonic wave is maintained by dividing the passage, so that good transmission and reception can be performed.

の 一 Further, since one side 67 of the vertical cross section of the divided passage is longer than half a wavelength, the propagation path is less affected by the viscosity of the fluid flowing along the divided surface and can be reduced in attenuation. Furthermore, by setting the length of one side 67 not to be an integral multiple of the wavelength, it is possible to suppress the resonance in the lateral direction, and it is possible to propagate the light efficiently.

In addition, by using the divided passage for the measurement flow path including the inflow suppressing body such as the first inflow suppressing body and the second inflow suppressing body, the turbulence of the flow in the opening hole can be further reduced. To improve the measurement upper limit.

According to the above embodiments, the following effects can be obtained as is clear from the above description.

The ultrasonic flow rate measuring device of the embodiment is provided at least in the vicinity of the opening on the downstream side to reduce the flow of the fluid to be measured into the opening, and is provided on the upstream side of the measurement flow path. A second inflow restrictor for reducing the flow of the fluid to be measured into the opening; and a first inflow restrictor provided in the downstream opening has an at least one ultrasonic transmission opening. Unit, so that the flow between the ultrasonic transmitter and receiver is stabilized and the reception level of the ultrasonic wave is increased to increase the measurement accuracy and the upper limit of the flow rate measurement. , The drive input of the ultrasonic transceiver can be reduced.

Further, the ultrasonic flow measurement device of the present embodiment has a first inflow suppressing body and a second inflow suppressing body that reduce the flow of the fluid to be measured into the opening hole with respect to the forward and reverse flow of the fluid to be measured. The first inflow suppressor provided in the downstream opening hole at the time of forward flow is an opening hole sealing portion having at least one ultrasonic transmission port, and the second inflow suppressor is an inlet of the measurement flow path. Even when instantaneous reverse flow occurs due to pulsating flow, the flow of the fluid to be measured into the opening hole is reduced as in the case of forward flow, and the ultrasonic The turbulence of the flow between the transmitter and the receiver can be greatly reduced, the measurement accuracy can be increased, and the upper limit value for the flow rate measurement can be increased.

Further, the ultrasonic flow rate measuring apparatus of the present embodiment is a propagation path flow restriction having a restriction section disposed along the ultrasonic transmission path between the upstream and downstream ultrasonic transceivers and exposed in the flow. The turbulence of the flow is promoted by the regulating part of the propagation path flow regulating body located immediately upstream in the whole area from the upstream side to the downstream side of the ultrasonic wave propagation path. The flow condition is evenly turbulent over the entire width direction of the ultrasonic propagation path from the area near the upstream opening to the area near the downstream opening, reducing the change in the correction coefficient over the entire flow measurement range. The measurement accuracy can be improved by preventing the error from increasing due to the correction coefficient, and the measurement accuracy can be maintained even if the Reynolds number changes due to the change in the kinematic viscosity coefficient of the fluid. change Can achieve strong measuring device for, it is possible to improve the practicability.

Further, the ultrasonic flow rate measuring apparatus of the present embodiment is a propagation path flow restriction having a restriction section disposed along the ultrasonic transmission path between the upstream and downstream ultrasonic transceivers and exposed in the flow. Body, and an inflow suppressor that reduces the flow of the fluid to be measured into the opening hole, and the flow path is regulated by a propagation path flow restrictor disposed immediately upstream in the entire region from the upstream side to the downstream side of the ultrasonic propagation path. The turbulence is promoted, and the flow state is uniformly turbulent throughout the width of the ultrasonic wave propagation path from the area near the upstream opening to the area near the downstream opening regardless of the flow rate. The change in the correction coefficient can be reduced over the entire flow rate measurement range, the error due to the correction coefficient can be prevented from increasing, and the measurement accuracy can be increased. To Location and the turbulence of the flow of by reducing the flow of the open hole in the ultrasonic wave propagation path between the ultrasonic transducers can be greatly reduced, it is possible to increase the upper limit value that can flow measurement.

Further, the first inflow suppressing member provided in the upstream opening is a flow deflector, and the ultrasonic transmission / reception unit eliminates the ultrasonic wave propagation loss due to the ultrasonic passage opening in the upstream opening. In addition to reducing the drive input, the flow of fluid into the upstream opening can be reduced, and the turbulence of the flow in the ultrasonic wave propagation path can be stabilized to improve the measurement accuracy.

In addition, the first inflow suppressing member provided in the upstream opening hole includes an opening hole sealing portion having at least one ultrasonic transmission port, and the flow of the fluid into the upstream and downstream opening holes is provided. A drastic reduction in inflow can be realized, the upper limit value of the flow rate measurement can be increased, and the measurement accuracy can be improved even for a flow accompanied by a backflow. Ultrasonic transmission and reception with excellent N characteristics can be realized, transmission output can be reduced, and power consumption can be reduced by reducing drive input.

In addition, the opening ratio of the opening sealing portion provided in the upstream opening is larger than the opening ratio of the opening sealing portion provided in the downstream opening, thereby reducing the propagation loss of ultrasonic waves. Thus, it is possible to improve the upper limit value of the flow rate measurement and the measurement accuracy for the backflow, and to reduce the power consumption by reducing the drive input to the ultrasonic transceiver.

In addition, the propagation path flow restricting member is disposed on the upstream side and the downstream side of the ultrasonic wave propagation path, and surrounds the ultrasonic wave propagation path with the upstream side and the downstream side propagation path flow restricting body. By equalizing the turbulence state from the upstream side to the downstream side, the correction coefficient can be further flattened, the measurement accuracy can be further improved, and the flow state on the downstream side of the measurement flow path by the downstream propagation path flow restrictor The effect of the measurement is reduced and stable measurement is realized irrespective of the piping condition on the downstream side of the measurement device, the degree of freedom of installation of the measurement device can be improved, and furthermore, either the forward direction or the reverse direction in the measurement flow path The same effect can be obtained for the flow, and the measurement accuracy can be improved by stabilizing the correction coefficient for the pulsating flow.

Also, the propagation path flow restrictors disposed on the upstream and downstream sides of the ultrasonic propagation path are integrated via a connecting portion, and the installation distance between the propagation path flow restriction bodies or the restriction on the upstream and downstream sides is established. It is possible to realize a measurement device that is stabilized by preventing the displacement of the parts from each other and that has little variation. Further, since the propagation path flow regulating body is reinforced by the connection section, the regulation section can be made finer or thinner, and the flow state in the ultrasonic propagation path can be equalized or the pressure loss in the measurement flow path can be reduced. .

In addition, the propagation path flow restrictors and the inflow restrictors disposed on the upstream and downstream sides of the ultrasonic propagation path are integrated, so that the upstream and downstream propagation path flow restrictors and the inflow restrictors are not The positional relationship such as the distance is determined and the flow state can be stabilized, the dispersion of the flow state in the ultrasonic propagation path can be reduced, and stable measurement with small dispersion can be realized. The strength of the flow control body can be further reinforced, and deformation can be prevented over a long period of use, thereby improving durability and reliability.

In addition, the inflow suppressing body is a first inflow suppressing body provided in the downstream opening, and the inflow suppressing body is provided in the downstream opening in which a stronger vortex easily intersects the flow at an acute angle. Is arranged to reduce the flow into the opening hole, the turbulence of the flow between the ultrasonic transceivers can be efficiently reduced, and the upper limit of the flow rate measurement can be increased.

Further, the inflow suppressor is a first inflow suppressor provided in the upstream and downstream opening holes, and the turbulence in the opening hole that accounts for a large proportion of the flow disturbance in the ultrasonic wave propagation path. Can be efficiently reduced, and the measurement accuracy and the upper limit value at which the flow rate can be measured can be increased.

Also, the inflow suppressor is a second inflow suppressor provided with an inflow suppressor in a propagation path flow restrictor arranged along the ultrasonic propagation path, and is an integral part of the propagation path flow restrictor and the inflow suppressor. Thus, the variation in the characteristic of suppressing the inflow into the opening hole can be reduced to improve the reliability, and the compact ultrasonic propagation path can be formed, so that the measurement flow path can be downsized.

Further, the inflow suppression body includes a first inflow suppression body provided in the opening hole, and a second inflow suppression body provided with an inflow suppression unit in the propagation path flow regulating body, and a first and a second inflow suppression body. Measurement accuracy and reliability can be improved by reducing turbulence in the opening hole due to the synergistic effect of the two inflow suppression bodies and reducing the variation in inflow suppression characteristics into the opening hole by integrating the propagation path flow control body and the inflow suppression body. Since a compact ultrasonic wave propagation path can be formed, the measurement flow path can be reduced in size.

Further, the first inflow suppressing body is an opening hole sealing portion having at least one ultrasonic transmission port, and the inflow of the fluid to be measured into the opening hole is achieved by covering the opening hole with the opening hole sealing portion. The suppression effect can be further enhanced, and the flow in the opening hole can be reduced and stabilized.

Further, the first inflow suppressor includes an opening hole sealing portion having at least one ultrasonic transmission port and a flow deflecting portion provided in the vicinity of the opening hole. By further improving the suppression effect, the measurement accuracy can be further improved, and the flow deflector can reduce the adhesion of foreign substances such as dust to the opening hole sealing portion. It is possible to select the ultrasonic wave with high flexibility without putting the ultrasonic wave first, and it is possible to realize a device with lower power consumption or higher sensitivity and higher measurement accuracy by further increasing the ultrasonic wave permeability.

In addition, the opening ratio of the opening sealing portion provided in the upstream opening is larger than the opening ratio of the opening sealing portion provided in the downstream opening, thereby reducing the propagation loss of ultrasonic waves. Thus, it is possible to improve the upper limit value of the flow rate measurement and the measurement accuracy for the backflow, and to reduce the power consumption by reducing the drive input to the ultrasonic transceiver.

Also, the opening hole sealing portion is a mesh of a slanted mesh having a slope with respect to the horizontal, and by tilting with respect to the horizontal, the fall of fine powder such as dust attached to the slanted mesh is promoted. By reducing the amount of deposition and preventing clogging of the mesh, propagation of ultrasonic waves can be ensured, stable measurement accuracy can be maintained over a long period of time, and durability and reliability can be improved.

In addition, the flow deflectors are provided on the upstream and downstream sides of the opening, so that the measurement accuracy can be further improved and the flow into the opening can be improved in both forward and reverse directions of the measurement flow path. Suppression and foreign matter intrusion into the opening can be suppressed, and stable measurement accuracy can be maintained for a long period of time even if pulsating flow is accompanied by backflow, so that durability and reliability can be improved.

In addition, the propagation path flow restricting body changes the installation distance from the ultrasonic wave propagation path according to the type of the fluid to be measured. The road can be shared and the convenience can be improved, and stable measurement accuracy can be maintained regardless of the fluid to be measured. Further, the cost can be reduced by sharing the measurement flow path.

規 制 Further, since the regulating portion of the propagation path flow restricting body is formed of a mesh, the installation space of the propagation path flow restricting body can be made thinner and smaller in the flow direction, and the measurement flow path can be downsized.

In addition, the regulating portion of the propagation path flow regulating body is formed by a lattice having a wall surface in the flow direction, and the flow direction in the ultrasonic propagation path is further improved by regulating the flow direction by the wall surface extending in the flow direction. Equalization can improve measurement accuracy.

The two regulating portions adjacent to each other in the propagation path flow regulating body are different in the mutual distance depending on the position of the cross section of the measurement flow path, and each regulating portion is opened while keeping the length in the flow direction small. By optimizing the size according to the position of the cross section of the measurement flow path, the flow velocity distribution in the ultrasonic wave propagation path can be made more uniform, and the length of the regulating section in the flow direction can be reduced, so that pressure loss is reduced and flow velocity is reduced. It is possible to improve the measurement accuracy by equalizing the distribution.

In addition, the cross section orthogonal to the flow of the measurement flow channel is a rectangular shape, and the rectangular cross section can increase the ratio of the measurement area in the measurement cross section, and the same conditions are applied to the flow from the upstream side to the downstream side of the ultrasonic wave propagation path. The average flow velocity of the fluid can be measured with high accuracy because the measurement can be performed by the method and the two-dimensional flow in the measurement flow path can be promoted. Further, by providing the second inflow suppressing body, the two-dimensional flow can be further promoted.

The cross section orthogonal to the flow of the measurement flow path is a rectangle having an aspect ratio smaller than 2, so that it is not necessary to increase the aspect ratio to cause a two-dimensional flow, and reduce the cross section specification to reduce interference of reflected waves. It can be set freely according to the height of the flow path, and can transmit and receive ultrasonic waves with enhanced sensitivity. Further, the pressure loss of the measurement flow path can be reduced as a cross section in which the length of contact with the fluid is reduced without excessively flattening the measurement cross section.

The shape of the opening hole into the measurement flow path has a side in a direction substantially orthogonal to the flow direction of the measurement flow path, and is uniformly superimposed in the height direction of the measurement flow path. Sound waves can be transmitted and received, and the size of the opening in the measurement flow path in the flow direction can be shortened, so that the flow disturbance due to the opening can be further reduced and the measurement accuracy can be further improved.

In addition, a drift suppression body with a flow opening with a fine opening is provided at the introduction part located upstream of the measurement flow path, and a stable flow is measured regardless of the flow path shape and pipe shape on the upstream side By supplying the flow to the flow path, turbulence of the flow between the ultrasonic transceivers can be reduced, the upper limit value that can be measured can be further increased, and the measurement accuracy can be further improved. Further, stable measurement can be realized regardless of the flow path shape and the pipe state on the upstream side of the measurement flow path, and the degree of freedom of installation of the measuring device can be improved.

In addition, a drift suppression body having a flow opening having a fine opening is provided at an introduction portion disposed upstream of the measurement flow path and a discharge portion at the downstream side. By supplying a stable flow to the measurement flow path even with a fluid to be measured that has a pulsation source on the side, the turbulence of the flow between the ultrasonic transmitter and receiver can be reduced, the upper limit value that can be measured can be further increased, and the measurement accuracy can be improved. Can be further improved. In addition, stable measurement can be realized regardless of the shape of the flow path on the upstream or downstream side of the measurement flow path, the state of the pipe, or the source of pulsation, and the degree of freedom of installation of the measurement device can be further improved.

In addition, the cross-sectional area of the inlet or outlet is larger than the cross-sectional area of the measurement flow path, and the installation cross-sectional area of the drift suppression body is increased to reduce the pressure loss of the drift suppression body and increase the pressure loss. In addition, a large cross section of the inlet or outlet makes it possible to mount the measuring device without changing the shape of the inlet or outlet even if the upstream or downstream channel shape or piping shape is different. It is possible to realize a measuring device that can be installed and has a high degree of freedom in installation.

In addition, the opening size of the flow opening of the drift suppression body is smaller than the opening size of the flow opening provided in the second inflow suppression body, and the upstream or downstream connection port is arranged to be offset in position. Even if the measurement fluid is flowing evenly in the measurement flow path, accurate measurement can be performed, and even if there is pulsation in the fluid to be measured, the pulsation is reduced in the measurement flow path by the small opening size flow port And the measurement accuracy can be improved even for a pulsating flow. Furthermore, the small-sized flow opening of the drift suppression body can reduce intrusion of dust, dust, and the like into the measurement section, and can increase the reliability of the measurement operation in the measurement flow path.

Further, the ultrasonic flow measurement device of the present embodiment includes a measurement flow path through which a fluid to be measured flows, an ultrasonic transceiver provided on the upstream side and the downstream side of the measurement flow path, and the ultrasonic transceiver described above. Upstream and downstream openings facing the flow path, at least one of the openings having a plurality of divided passages extending along the propagation direction of the ultrasonic wave, Since the light propagates in the fluid in the passage, the sensitivity is low, and by dividing the passage, the straightness of the ultrasonic wave is maintained, and good transmission and reception can be performed. The open flow path is divided into small parts, so that vortices are not easily generated, the flow of fluid into the inside of the open hole can be reduced, and even if pulsation occurs, the flow rate can be correctly measured.

In addition, at least one of the opening holes has a plurality of divided passages extending along the propagation direction of the ultrasonic wave, and the inflow suppressing body can reduce the flow into the opening hole, improve the measurement upper limit value, and improve the ultrasonic wave. Is transmitted through the fluid in the divided flow path, so that the sensitivity is less reduced, and by dividing the passage, the straightness of the ultrasonic wave can be maintained, good transmission and reception can be performed, and the opening provided on the side surface of the flow path The opening flow path inside the hole is divided into small parts, making it difficult for vortices to be generated, and further reducing the inflow of fluid into the opening hole, making it possible to correctly measure the flow rate even if pulsation occurs .

Each of the divided passages has an entrance surface along the vibration surface of the ultrasonic transceiver and an exit surface along the channel wall surface, and the ultrasonic wave is perpendicularly incident on the divided passage, and enters the divided passage. It can travel straight along the path, it can be an ultrasonic wave propagation path that does not cause reflection etc. and has little attenuation, and the outlet becomes a flat surface with respect to the flow path wall surface, and the flow of the boundary layer of the flow path wall surface And ultrasonic waves can be efficiently emitted by aligning the exit surfaces as emission surfaces.

Further, each of the divided passages of one of the opening holes extends on the same straight line as the corresponding divided passage of the other of the opening holes, so that the transmitting surface and the receiving surface are aligned along the traveling direction of the ultrasonic wave. Thus, the return loss can be reduced by the partition plates of the divided passages of the opposed opening holes.

Further, one side of the vertical cross section of each of the divided passages has a length longer than a half wavelength of the ultrasonic wave used for transmission / reception, so that the divided passage is less susceptible to the influence of the viscosity from the divided surface and can be reduced in attenuation.

の 一 Further, one side of the vertical cross section of each divided passage has a dimension that is not an integral multiple of a half wavelength of the ultrasonic wave used for transmission and reception, so that resonance in the horizontal direction can be suppressed, and transmission can be performed efficiently.

In addition, the distance between the divided passage of the opening hole and the corresponding vibration surface of the ultrasonic transmitter / receiver is an integral multiple of a half wavelength of the ultrasonic wave. Can do well.

The thickness of the partition forming the divided passage is shorter than the wavelength of the ultrasonic wave used for transmission and reception, so that reflection of the ultrasonic wave can be prevented and transmission and reception can be performed efficiently.

分割 Furthermore, a honeycomb lattice material is fitted into the opening hole to form a divided passage, and by forming a lattice, the opening hole can be divided in the vertical and horizontal directions.

分割 One of the divided passages is provided with an opening at the center of the opening, and the opening matches the center of the ultrasonic transceiver so that transmission and reception can be performed efficiently.

The length of each of the divided passages is shorter than the wavelength of the ultrasonic wave used for transmission / reception, so that the ultrasonic wave propagation path can be reduced in attenuation.

Further, in the opening hole, a mesh material is arranged in a direction perpendicular to the propagation direction of the ultrasonic wave to form a divided passage, and by dividing the opening hole with a mesh, the passage length can be minimized. it can.

The divided passage has a communicating portion that connects each passage with an adjacent passage in the middle of the passage, so that attenuation by the partition plate can be minimized.

よ う As is clear from the above description, the ultrasonic flow rate measuring device of the present invention can measure the flow rate with high accuracy using ultrasonic waves, and is suitable for measuring fluid such as gas.

1 is a cross-sectional view illustrating a configuration of an ultrasonic flow rate measurement device according to a first embodiment of the present invention. FIG. 1 is a sectional view of a first inflow suppressing body in FIG. 1. Sectional view of another first inflow suppressor Configuration sectional view of an ultrasonic flow rate measuring device showing another first inflow suppressing body Sectional drawing of another 1st inflow suppression body in Example 1. FIG. 4 is a front view showing another example of the opening hole sealing portion in FIG. 4. FIG. 1 is a cross-sectional view taken along line AA of the measurement channel in FIG. 1. Front view of opening hole in FIG. 2 is a sectional view showing the configuration of an ultrasonic flow rate measuring apparatus according to a second embodiment of the present invention. Top view of the introduction part of the second embodiment BB line sectional view of the measurement flow path in FIG. 9 Configuration sectional view of an ultrasonic flow measurement device showing another drift suppression body 3 is a cross-sectional view illustrating a configuration of an ultrasonic flow measurement device according to a third embodiment of the present invention. Sectional drawing of another 1st inflow suppression body in Example 3. Embodiment 4 Cross-sectional view of the configuration of an ultrasonic flow measurement device according to a fourth embodiment of the present invention. Front view of the flow direction of the propagation path flow restrictor in the fourth embodiment. FIG. 15 is a characteristic diagram of a correction coefficient when there is no propagation path flow restrictor in FIG. 4 is a characteristic diagram of a correction coefficient when there is a propagation path flow restrictor according to a fourth embodiment of the present invention. Sectional drawing which shows another propagation path flow regulating body of Example 4. Configuration sectional view of an ultrasonic flow measurement device showing another propagation path flow restricting body of the fourth embodiment. FIG. 17 is a perspective view showing another propagation path flow restricting body of the fourth embodiment. FIG. 20 is a cross-sectional view taken along line AA of the propagation path flow restricting body in FIG. 20. Sectional view showing installation position of propagation path flow restrictor A perspective view showing another propagation path flow restricting body. A perspective view showing another propagation path flow restricting body. Front view of another propagation path flow restrictor viewed from the flow direction Embodiment 5 Cross-sectional view of the configuration of an ultrasonic flow measurement device according to a fifth embodiment of the present invention. Sectional drawing which shows the inflow suppression body of Example 5. Sectional drawing which shows another inflow suppressing body of Example 5. Sectional drawing which shows another inflow suppression body of an Example. Sectional drawing which shows another inflow suppressing body of Example 5. Sectional view of an ultrasonic flow measuring device showing another example of the fifth embodiment. Perspective view showing another example of the inflow suppressing body and the propagation path flow regulating body of the fifth embodiment. Sectional view of the flow path of the ultrasonic flow measuring device showing the sixth embodiment of the present invention. Sectional View of Opening Hole in Example 6 Sectional drawing which shows the positional relationship between the opposing ultrasonic transceivers in Example 6. FIG. 14 is a front view showing the exit surface of the first split passage in the sixth embodiment. FIG. 14 is a front view showing the exit surface of the second divided passage in the sixth embodiment. FIG. 14 is a front view showing the exit surface of the third divided passage in the sixth embodiment. FIG. 14 is a front view showing the exit surface of the divided passage in the sixth embodiment. Sectional view showing a communicating portion of a divided passage in Embodiment 6. Sectional view showing another example of the divided passage in the sixth embodiment. FIG. 42 is a front view showing the exit surface of the divided passage in FIG. 42. Configuration diagram of conventional ultrasonic flow measurement device Configuration diagram of another conventional ultrasonic flow measurement device

Explanation of reference numerals

Reference Signs List 6 Measurement flow path 8, 9 Ultrasonic transmitter / receiver 11, 12 Opening hole 13 Ultrasonic propagation path 19 Measurement control unit 20 Operation unit 21 Opening hole sealing unit 22 Ultrasonic passage port 43, 45 Propagation path flow regulating body 44 Regulation unit 56 inflow suppressor 58 first inflow suppressor 58a flow deflector

Claims (7)

A measurement channel through which the fluid to be measured flows, an ultrasonic transceiver provided on the upstream side and the downstream side of the measurement channel, an opening hole for allowing the ultrasonic transceiver to face the measurement channel, and an upstream side and a downstream side. A propagation path flow restrictor having a restriction section disposed along the ultrasonic propagation path between the ultrasonic transmitters and receivers on the side and exposed in the flow, and measuring the propagation time of ultrasonic waves between the ultrasonic transmitters and receivers An ultrasonic flow rate measuring device, comprising: a measurement control unit that performs a calculation; 2. The ultrasonic flow rate measuring device according to claim 1, further comprising an inflow restricting body that reduces the flow of the fluid to be measured into the opening hole. 3. The ultrasonic flow rate measuring device according to claim 2, wherein the first inflow suppressing member provided in the opening on the upstream side is a flow deflector. (3) The ultrasonic flow rate measuring device according to (2), wherein the inflow suppressing body is an opening hole sealing portion having at least one ultrasonic transmission port. 2. The ultrasonic flow measurement device according to claim 1, wherein the propagation path flow restricting member is arranged on an upstream side and a downstream side of the ultrasonic wave propagation path. The ultrasonic flow measurement device according to claim 5, wherein the propagation path flow restrictors disposed on the upstream side and the downstream side of the ultrasonic propagation path are integrated via a connecting portion. 2. The ultrasonic flow rate measuring device according to claim 1, wherein the propagation path flow restricting body changes an installation distance from the ultrasonic propagation path according to a type of the fluid to be measured.

Images