JP4503034B2 - Flowmeter - Google Patents

Description

  The present invention relates to a flow meter such as a water meter, and more particularly to a vertical Waltman flow meter.

  As shown in FIG. 16, the conventional vertical Waltman type flow meter passes through the strainer 106 and then passes through the supplementary pipe 102, and the fluid to be measured enters the lower case inlet 103 once at the A portion. It moves down after reaching the staying part B under the impeller for measuring the amount of fluid. The fluid to be measured whose flow is disturbed is rectified by the radial rectifying plate 105 installed in the rectifier 104, and the impeller 107 installed in the bipot 106 is rotated to change the flow downward again at C part. Go to the case outlet 108.

  However, the fluid flowing in the flowmeter has a large pressure loss due to repeated expansion and contraction of the passage area and the influence of many rectifying plates installed in the rectifier, which causes a decrease in capacity and peaks. It was a cause of instrumental error.

  Also, if too many rectifying plates are installed, there is a problem that the pressure loss increases or the peak of the instrumental difference begins to flow out from a large flow rate, so rectifying effectively by installing the minimum number of rectifying plates where the flow is disturbed It was necessary to let them. In addition, the center may be shifted depending on the combination of the lower case, the rectifier, and the rectifier plate, which causes a difference in the amount of current that occurs due to the occurrence of drift.

  An object of the present invention is to provide a flow meter that alleviates the reduction in capacity and the occurrence of instrumental error peaks due to repeated expansion and reduction of the flow area of the fluid to be measured in the flow meter, and many rectifier plates of the rectifier. There is to do. Another object of the present invention is to reduce the increase in pressure loss due to the influence of a large number of rectifying plates installed in the rectifier, and to alleviate or prevent the problem that the peak of the instrumental difference starts from a large capacity. Is to provide. Still another object of the present invention is to provide a flowmeter that makes it difficult to shift the center of the combination of the lower case, the rectifier and the rectifier plate, and suppresses the occurrence of drift and hence the peak of instrumental error.

Means for Solving the Problems and Effects of the Invention

The present invention relates to a vertical Waltman type flow meter having an inlet and an outlet and in which an impeller for measuring a fluid flow rate is arranged in a vertical direction with respect to the inlet and the outlet.
The flow of the fluid to be measured introduced from the inflow port is changed in the direction along the axial direction of the impeller, the measured fluid is applied to the impeller, and the impeller is measured with respect to the extension of the center line of the inflow port. When the side closer to the upper side is the upper side, the side farther from the impeller is the lower side, the cross-sectional area of the inlet is S1, and the cross-sectional area of the introduction portion from the lower side with respect to the impeller is S2, the process from S1 to S2 As a change in the cross-sectional area, S2 / S1 is set to 0.7 to 1.4.

  In this way, by changing the passage cross-sectional area of the fluid path substantially constant or reducing the change, the flow accompanying the repeated expansion and reduction of the passage area of the flow path from the introduction of the fluid to the impeller to the impeller Turbulence and pressure loss are improved, the capacity of the flow meter can be increased, and the peak of instrumental error can be reduced. If the value of S2 / S1 is out of the above range, it is difficult to obtain the effect of improving the flow turbulence and pressure loss, so it is preferable to set the value within the above range.

  Further, the flow of the fluid to be measured is changed in the direction along the axial direction of the impeller by the L-shaped tube portion, and a bent plate of the L-shaped tube portion is provided with a current plate having a curved shape corresponding to the bent shape. Then, the fluid flows more smoothly, less turbulence of the flow, and pressure loss is reduced, so the capacity of the flow meter is further increased, and the instrumental error (allowable tolerance of metering of the flowmeter) is flatter. And can.

  Further, if a rectifier is provided close to the fluid inlet side of the impeller and the curved rectifier plate is installed integrally with the rectifier, the number of parts can be reduced, and the cost due to the increase in the number of parts. It is possible to prevent the rise, and the current plate can be easily formed and installed.

  Conversely, if a bent plate of the L-shaped tube part is formed integrally with the L-shaped tube part, a rectifying plate having a curved shape corresponding to the bent is formed on the bent part. By making the rectifying plate separately from the rectifier, a target shape can be created even for a shape in which resin molding cannot be performed integrally or the resin molding die becomes complicated.

  Also, by using 2 to 4 rectifying plates that support the bosses of the rectifiers that are provided close to the fluid inlet side of the impeller, pressure loss due to excessive rectification is reduced, and the instrumental error is flattened. Contribute to.

  Furthermore, a rectifier is provided close to the fluid inlet side of the impeller, and an edge that causes a contracted flow due to a throttling effect in a large capacity region is attached to the inner diameter side of the fluid inlet port of the rectifier. Improves the balance of instrumental error in the small flow rate region and large flow rate region, which also contributes to flattening of the instrumental error in another sense.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be described with reference to examples shown in the drawings.
The following example is a flow meter applied to a water meter, for example, and the fluid to be measured in that case is water.

  1 and 2, the flow meter 1 includes a supplementary pipe 10 and a main body 2 to which the supplementary pipe 10 is connected. The main body 2 is provided on a lower case 11 and an upper part of the lower case 11. A weighing device 3. The lower case 11 includes a straight tubular inflow pipe portion 12 connected to the supplementary pipe 10 and the joint 4, and an L-shaped bent portion bent at a right angle from the straight tubular inflow pipe portion 12 with a predetermined radius of curvature. A curved pipe section (hereinafter also referred to as an L-shaped pipe section or an L-shaped pipe) 16 and an L-shaped tubular outflow pipe portion 5 that guides the fluid to be measured through the impeller 15 of the measuring chamber 17 are provided.

  The measuring chamber 17 in the lower case 11 is located at the upper end of the vertical tube portion of the bent portion (L-shaped tube portion) 16, and the impeller 15 is inserted into the measuring chamber 17 by a vertical pivot (rotating support shaft) 14. It is housed rotatably in a horizontal plane. A center hole 6 that opens downward is formed at the center of the impeller 15, and the center hole 6 (FIG. 3) is loosely fitted to the pivot 14, and the impeller 15 is rotatable at the tip of the pivot 14. Supported. The impeller 15 includes a plurality of blades 15a spirally twisted around its center line, and is rotated by the fluid to be measured flowing from substantially vertically below.

  The fluid to be measured that has passed through the rotating impeller 15 flows out from the opening on the outer periphery of the measuring chamber 17 outward in the radial direction of the impeller 15, and the horizontal direction from the vertically lower side by the L-shaped outflow pipe portion 5. The direction is changed to a predetermined curvature and is led downstream. The rotational speed of the impeller 15 that is substantially proportional to the flow rate of the fluid to be measured is converted into a flow rate electronically or mechanically and measured by the measuring device 3 to display a predetermined flow rate.

  Near the lower side of the impeller 15, a rectifier 13 is fixed to the lower case 11. The rectifier 13 has an annular shape, and has a plurality of rectifying plates in the annular shape, for example, radially or in other arrangements, and has the pivot 14 at the center, which also serves as a support mechanism for the impeller 15. Yes. The fluid to be measured guided from below passes through the rectifier 13, is rectified by the rectifying plate, and then strikes the impeller 15.

  In this flow meter 1, the supplementary pipe 10 and the straight tubular inflow pipe portion 12 (inlet) are coaxial in the horizontal direction, and the outflow pipe portion 5 (outlet) is also coaxial. In other words, when the side closer to the impeller 15 is the upper side and the side farther from the impeller 15 is the lower side with respect to the extension of the center line of the supplemental pipe 10 and the inflow pipe portion 12, etc., the inflow pipe portion from the supplementary pipe 10 The fluid to be measured introduced through 12 is introduced straight and horizontally without being lowered downward, and flows as it is in the direction along the axial direction of the impeller 15 (vertically upward) by the L-shaped tube portion (L-shaped tube) 16 as it is. In this configuration, the fluid to be weighed is applied to the impeller 15 and measured.

  In the flow meter 1, the flow passage cross-sectional area (inlet cross-sectional area) of the inflow pipe portion 12 is S 1, and the cross-sectional area of the introduction portion from the lower side with respect to the impeller 15 (inner diameter of the rectifier 13 or impeller 15 S2 is a cross-sectional area corresponding to the outer diameter of S1). As a change in the cross-sectional area from S1 to S2, S1 and S2 are almost equal to each other, or the difference between the two is predetermined. It is assumed to be below the value. That is, S2 / S1 is defined in the range of 0.7 to 1.4 as a change in cross-sectional area from S1 to S2.

  The fluid to be measured that has passed through the strainer 9 and the supplemental pipe 10 enters the lower case 11. As described above, the inlet portion 12 extends from the supplementary pipe 10 so as to extend the straight pipe, and the fluid to be measured hits the impeller 15 on the pivot 14 installed in the rectifier 13 vertically. A straight pipe is bent at a right angle with a predetermined curvature like an L-shaped pipe to form an L-shaped pipe portion 16. At this time, if the impeller outer diameter of the impeller 15 and the inner diameters of the measuring chamber 17 and the rectifier 13 are not the same as the inner diameter of the supplementary pipe 10, the related pipe diameter that continues from the lower case inlet 12 is determined as the impeller 15 and the metering. In order to match the diameter in the chamber 17, it may be gradually changed to the target pipe diameter at the straight pipe portion (inflow pipe portion) 12 continuing from the supplementary pipe 10, or may be changed at the portion of the L-shaped pipe portion 16. May be. The radius of curvature of the L-shaped tube portion 16 should be as large as possible as long as the height and length of the flow meter allow in consideration of the effect on pressure loss and instrument differential performance.

  The rectifier 13 described above is provided in a portion of the L-shaped tube portion 16 that has been bent at a right angle from the horizontal to the vertical with a predetermined curvature radius. As shown in FIG. 2, a rectifying plate 19 is provided at the bent portion of the L-shaped tube portion 16 so as not to disturb the flow of the fluid to be measured. The rectifying plate 19 has a curvature (curved form) with a curvature substantially corresponding to the curvature of the bent portion of the L-shaped tube portion 16, and extends a predetermined length along the bend of the tube wall of the L-shaped tube portion 16. It is. On the plate surface of the rectifying plate 19 on the concave curved surface side, a rib 21 perpendicular to the rectifying plate 19 is formed so as to extend in a direction parallel to the center line of the L-shaped tube portion 16.

  As shown in FIG. 3, an appropriate number (for example, 1 to 4 sheets, preferably about 3 sheets) of the current plates can be used. When a plurality of current plates are provided, a plurality of current plates 20 are predetermined. They are provided substantially parallel to each other with a spacing and a similar radius of curvature. Further, an appropriate number (for example, one) of ribs is provided in the middle of the width direction of the rectifying plate 20 so as to intersect each rectifying plate 20 perpendicularly (so as to extend in a direction parallel to the center line of the L-shaped tube portion 16). 21 spans the current plates 19 and is formed integrally therewith. In other words, the ribs 21 connect the current plates 20 to ensure a certain strength. These rectifying plates 20 (or 19 described above) are connected to the lower end of the rectifier 13 and are supported by the rectifier 13 in a fixed position.

  As described above, for example, if the bent portion is the L-shaped tube portion 16, such a rectifying plate is parallel rectified so as to minimize the pressure loss in accordance with the curvature radius of the L-shaped tube portion 16. The number of plates 20 may be increased. It is desirable that the rib 21 that intersects the rectifying plate 20 perpendicularly has a minimum shape that maintains the strength of the rectifying plate 20 in order not to increase the pressure loss. Moreover, as for the several baffle plate 20, it is desirable to install in the bending part of the L-shaped pipe part 16 as mentioned above.

  In addition, like the baffle plate 22 shown in FIG. 4, it may be installed not only on the bent portion on the inflow side or the L-shaped tube portion but also on the bent portion (outflow tube portion) 5 on the outflow side. Good. That is, the rectifying plate 22 having a convex curved surface that protrudes downward is provided alone or the L-shaped tube portion 16 on the inflow tube portion 12 side so as to substantially correspond to the curvature of the outflow tube portion 5. It can be provided together with the rectifying plate 19 or 20 at the bent portion. When such a rectifying plate 22 is provided on the outlet side, it is most preferable to manufacture the rectifying plate 22 integrally with the lower case 23 or integrally by casting or the like in consideration of the strength of the rectifying plate 22. Although the above rectifier plates 19, 20, and 22 are assumed to be installed in a flow meter having an L-shaped tube portion 16, a conventional tube-type flow meter such as a rectifier plate 24 shown in FIG. May be installed. Here, the pipe shape shown in FIG. 5 (same as in FIG. 16) is such that the fluid entering from the inflow port once falls down at the bent pipe part and reaches the lower part of the impeller, and rises while staying at the lower part of the bent pipe part. The rectifying plate 24 can be installed in correspondence with the bent pipe portion.

  Furthermore, as shown in FIG. 6, the rectifying plate 25 installed in the bent portion can be reduced in the number of parts by making it integrally with the rectifier 26, thereby preventing an increase in cost. In this example, the vicinity of the center of the rectifier 26 is a lower protruding portion that protrudes downward, and the rectifying plate 25 (this is the rectifying plate 19 or 20 in FIG. 2 or 3) integrally with the lower protruding portion. Of the same form). In that case, the rectifying plate 25 and the rectifier 26 can be obtained by integral molding of resin. In the example shown in the figure, the bent tube portion is the L-shaped tube 16, but may be applied to the flowmeter having the conventional tube shape shown in FIG. 5.

  On the contrary, the rectifying plate 19 or 20 installed at the bent portion of the L-shaped tube portion 16 is impossible to be integrated with the rectifier 13, and the molding die becomes complicated. It is possible to create even a shape that would end up (FIG. 2). The method of installing the rectifying plate 19 or 20 created separately is that, for example, the screw 27 forms the boss 7 of the rectifier 13 (the central side of the rectifier 13, and from here, for example, the rectifying plate radially or otherwise in a portable arrangement (A rectifying blade) is formed) (FIG. 2), a method in which the rectifying plate 19 or 20 is fixed to the boss portion 7 of the rectifier 13 with a screw 27 and a nut 28 (FIG. 3), and an inlay 29 is formed and fitted. There are a method (FIG. 7) and a method using a spring.

  The inlay 29 is formed as a fixing connecting portion on a part (for example, the upper end portion) of the rectifying plate 19 or 20, and the fixing connecting portion 29 is connected to the housing of the L-shaped tube portion 16 and the rectifier 13 (measurement). It is sandwiched and fixed at the joint portion with the case 17 of the chamber 17. An engaging step 8 is formed at the end of the L-shaped tube portion 16 and / or the rectifier 13 in order to sandwich the fixing connecting portion 29, and the fixing connecting portion 29 is connected to the engaging step 8. It is inserted and held between the rectifier 13 and the L-shaped tube portion 16 via the seal 9 and held. The above example may be applied to the conventional pipe-shaped flow meter shown in FIG.

  As shown in FIG. 12, when the rectifier plate (represented by 19) installed in the bent portion of the L-shaped tube portion 16 is installed in the rectifier 13, the tip 30 of the rectifier plate 19 is circular in consideration of assembly. Become smaller. In order to solve this problem, as shown in FIG. 8, the current plate 31 (the configuration is the same as that of the current plate 19 and the like) can be manufactured integrally with the lower case 32. That is, the size reduction as in the case where the rectifying plate 31 is formed integrally with the tube wall of the lower case 32 by casting or the like and manufactured integrally with the rectifier 13 is eliminated.

  In that case, as shown in FIG. 8, the rectifying plate 31 is installed only on the bent portion 33 of the L-shaped pipe portion 16, and the bent portion 33 continues from the straight pipe portion 35 of the inflow conduit as shown in FIG. 9. There is a mode in which the rectifying plate 34 is installed integrally with the lower case 35, but it is preferable that the rectifying plate 34 is installed only in the bent portion 33 in terms of reducing frictional resistance due to the wall surface to the fluid to be measured. In the above example, the flow meter has the L-shaped tube 16 at the bent portion, but it can also be applied to the flow meter having the conventional tube shape shown in FIG.

  Furthermore, as shown to FIG. 10A-FIG. 10B, the rectification | straightening plate 37 of the rectifier 36 just under the impeller 15 can be made into 2-4 sheets. In the example of FIG. 10A, four rectifying plates 37 are installed on the boss portion 7 of the rectifier 36 at an equal angular interval of 90 degrees (in a cross shape). In the example of FIG. 10B, one of the four sheets is omitted, and three rectifying plates 37 are provided asymmetrically. Further, in the example of FIG. 10C, the two rectifying plates 37 on both sides with respect to the center of the rectifier 36 among the four rectifying plates 37 are eliminated, and the two rectifying plates 37 are 180 in the radial direction with the boss portion 7 interposed therebetween. It is installed at an angular interval of degrees.

  Thus, the flatness of the instrumental difference can be increased by reducing the number of the rectifying plates 37 (usually about 6 to 10 sheets are conventionally used). When a plurality of rectifying plates 20 are arranged on the L-shaped tube portion 16 (bent portion), the rectifying plate that does not contact the rectifying plate 37 installed to support the boss diameter (boss portion 7) of the rectifier. The distance between 20 (both sides a and b except for the central one: FIG. 3) and the impeller 15 is preferably 5 mm or more. In the above example, the flowmeter having the L-shaped tube 16 in the bent portion is described, but it can also be applied to the conventional tube-shaped flowmeter shown in FIG.

  As shown in FIG. 11, in order to provide a flow path narrower than the tube inner diameter of the L-shaped tube portion 16 at the inlet portion of the rectifier 40 or upstream (upward) thereof, the vertical direction of the L-shaped tube portion 16 is provided. An open end face (edge) 41 that is substantially perpendicular to the center line of the tube portion (upper part) can be formed. This edge 41 is a resistance against the flow of the fluid to be measured from the L-shaped tube portion 16 toward the impeller 15, and is a step-like throttle portion (in a substantially right angle with respect to the flow path) that is located inward from the flow wall surface. The lower end (inlet side) opening end surface) of the rectifier 40 formed from a flat surface.

  In other words, the edge 41 serves as a contraction imparting section that narrows the diameter of the fluid to be measured (the cross-sectional area of the flow path) from the L-shaped tube section 16 toward the impeller 15 and generates a contracted flow (contracted flow). Function. The diameter reducing action by the edge 41 (constricted flow imparting portion) is weak when the flow rate of the fluid to be measured is small, and becomes strong as the flow rate is large. If the diameter reducing action becomes stronger, the flow speed increases due to the throttling effect, and the force to turn the impeller 15 also increases. Therefore, it can be said that the larger capacity (high flow speed) region acts to increase the measurement sensitivity.

  The drift generated upstream from the inlet of the rectifier 40 is drowned out by the contracted current generated by the edge 41 of the inlet inner diameter of the rectifier 40, so that the influence on the measurement is reduced. Also, as described above, the flow rate is increased by the contraction flow by the edge 41 at a large capacity, and conversely, the contraction flow by the edge 41 does not occur at a small flow rate, so the apparent peak is lowered. Due to the above two effects, a flat instrumental difference can be realized.

  In this example, the flow to be measured is applied to the impeller by changing the flow in the direction along the axial direction of the impeller by the L-shaped pipe portion without lowering the measured fluid introduced from the inlet. As mentioned above (Fig. 5), the fluid that enters from the inflow port is once lowered at the bent pipe part and reaches the lower part of the impeller, and the lower part of the bent pipe part. The above-mentioned edge 41 is also formed in the rectifier of the flow meter in the type that rises while impinging and hits the impeller, and the above-mentioned effect is obtained by positively generating a contraction in a large flow rate region. You can also.

As described above, the pipe of the fluid to be measured leading from the inlet 12 side to the impeller 15 is bent at a right angle by the L-shaped pipe portion 16 from the horizontal to the vertical without being lowered downward, and By reducing the cross-sectional change from the inflow side to the impeller 15 (removing the staying part), there are few bent parts in the flow path, there is almost no staying part, and the fluid flow is less disturbed and the pressure loss Decrease. As a result, the capacity of the flow meter has increased. Specifically, it was confirmed that the capacity of the conventional product was 42 (m ³ / h), whereas the capacity of the product of the present invention was increased to 56 (m ³ / h).

  Moreover, in the Example which provided the baffle plate (typically 19, 20 etc.) curved along the curve in the curved part (bent part of the L-shaped pipe part 16) of the above flowmeters, In addition to this, the flow of the fluid to be measured becomes smoother. Therefore, as shown in FIG. 13, the flow meter is substantially free from the peak of instrumental error (measurement error (tolerance) of the flow meter). Incidentally, in the conventional product, an instrumental error peak occurs in a small flow rate region, but it can be seen that such an instrumental error peak does not exist in the flowmeter of the present invention.

  Moreover, in addition to the pipe line structure as shown in FIGS. 1 and 2, as shown in FIGS. 10A to 10C, it is necessary when the number of rectifying plates 37 (ribs) of the rectifier 36 is set to 2 to 4 sheets. As shown in FIG. 14, it was recognized that the instrumental difference from the middle flow rate range to the large flow rate range becomes extremely small due to the reduction of the pressure loss due to the above rectification.

  Further, since the edge 41 as shown in FIG. 11 is formed, the contracted flow hardly occurs in the small flow rate region, and the contracted flow occurs in the large flow rate region. As a result, as shown in FIG. 15, the instrumental difference in the small flow rate region is relatively large in the case without the edge 41, whereas the instrumental difference in the small flow rate region is reduced in the case with the edge 41. Was found to be obtained.

  In the above, the embodiment of the vertical Waltman type flow meter has been described with reference to FIG. 2 and the like assuming that the supplementary tube 10 is arranged horizontally and the impeller 15 is arranged vertically. Of course, the flow meter is generally installed and fixed in the arrangement of FIG. 2 and the like, but in the vertical Waltman type flow meter shown in FIG. 2 and the like, the supplementary tube 10 is vertically arranged such as vertical. Thus, it may be installed and fixed in an inverted posture in an angle range of 90 degrees or the like. Expressions such as “upper and lower”, “horizontal” and “vertical” in the above description are for convenience in order to simplify the description, and do not limit the essence of the invention.

The figure which shows the external appearance of the flowmeter which is an Example of this invention. FIG. Sectional drawing which shows the 1st modification (example of a some baffle plate) of FIG. Sectional drawing which shows the 2nd modification (example which has arrange | positioned the baffle plate in the outflow side) in FIG. Sectional drawing which shows the example which provided the curving-shaped baffle plate corresponding to the curved pipe part of the conventional pipe-shaped flowmeter. Sectional drawing which shows the 3rd modification (example which integrated the rectifier plate with the rectifier) of FIG. Sectional drawing which shows the 4th modification (example which installs a claim body to a rectifier by inlay) of FIG. Sectional drawing which shows the 5th modification (example which installs a baffle plate in a lower case) of FIG. Sectional drawing which shows the 6th modification (example which extended the baffle plate installed in the lower case to an inflow port) of FIG. 10A is a diagram showing an example in which four ribs (rectifier plates) are formed on the rectifier, FIG. 10B is a diagram showing an example in which three ribs (rectifier plates) are formed on the rectifier, and FIG. The figure which shows the example which formed two baffle plates. Sectional drawing which shows the example which formed the edge inside the inflow port of a rectifier. The perspective view which shows the example of the baffle plate integrated with a rectifier. The graph which shows the effect of the Example shown in FIG. 1, FIG. The graph which shows the effect of the example shown in Drawing 10A-Drawing 10C. The graph which shows the effect of the Example shown in FIG. The whole sectional view showing a conventional example.

Explanation of symbols

5 Outflow pipe part (outlet)
10 Supplementary tube 11 Lower case
12 Inlet pipe part (inlet)
13, 26, 36 Rectifier 15 Impeller 16 L-shaped tube portion 17 Weighing chambers 19, 20, 22, 24, 25, 31, 34, 37, 38, 39 Rectifier plate

Claims (6)

In a vertical Waltman type flow meter having an inflow port and an outflow port, and an impeller for measuring the flow rate of the fluid arranged in the vertical direction with respect to the inflow port and the outflow port,
The flow of the fluid to be measured introduced from the inlet is changed in a direction along the axial direction of the impeller, the fluid to be measured is applied to the impeller and measured, and the impeller is extended with respect to the extension of the center line of the inlet. When the side closer to the upper side is the upper side, the side farther from the impeller is the lower side, the cross-sectional area of the inlet is S1, and the cross-sectional area of the introduction part from the lower side with respect to the impeller is S2, the process from S1 to S2 A flow meter characterized in that S2 / S1 is set to 0.7 to 1.4 as a change in cross-sectional area.   2. The flow of the fluid to be measured is changed in a direction along the axial direction of the impeller by an L-shaped tube portion, and a bent plate of the L-shaped tube portion is provided with a rectifying plate having a curved shape corresponding to the curve. The flow meter described in 1.   The flowmeter according to claim 2, wherein a rectifier is provided adjacent to the fluid inlet side of the impeller, and the curved rectifier plate is installed integrally with the rectifier.   The flowmeter according to claim 3, further comprising: a rectifying plate having a curved shape corresponding to the bending of the bent portion of the L-shaped tube portion, the rectifying plate being formed integrally with the L-shaped tube portion. .   The flowmeter according to any one of claims 1 to 4, wherein a rectifier is provided close to the fluid inlet side of the impeller, and the number of rectifier plates that support the boss portion of the rectifier is two to four.   A rectifier is provided in the vicinity of the fluid inlet side of the impeller, and an edge is formed on the inner diameter side of the fluid inlet of the rectifier to cause the fluid passing therethrough to generate a contracted flow due to a throttling effect in a large capacity region. Item 6. The flow meter according to any one of Items 1 to 5.

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