JP2004333402A - Flow straightener and impeller-type flow meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow straightener and an impeller-type flow meter capable of improving measurement accuracy compared with conventional types. <P>SOLUTION: If an impeller-type flow meter 10 or a straightener 20 is used, fluid pressure to an impeller 40 is properly suppressed by a weir 80, and measurement accuracy can be improved compared with the conventional impeller-type flow meter 10. Here, the area of the section inside the weir where fluid passes is defined as A and the area of a section at the outlet piece of the impeller side where fluid passes is defined as B, the ratio R calculated by R=A/B is preferably 115 to 140%. By constituting the weir 80 with a slab-shaped ring fitted in the inner side of a casing 27 inside, by easy design changes in coupling the ring to the conventional flow straightener, the problem can be resolved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an impeller-type flowmeter and an impeller-type flowmeter for arranging a rectifier adjacent to a lower surface of an impeller, flowing fluid from the rectifier to the impeller, and measuring a flow rate based on rotation of the impeller. Rectifier provided.
[0002]
[Prior art]
FIG. 13 shows a conventional impeller type flow meter, and FIG. 13 is an enlarged view of the rectifier 2 provided in the impeller type flow meter. As shown in FIG. 13, in this impeller flow meter, the support pin 7 stands upright from the upper surface of the center rectifier 3 provided in the rectifier 2, and the impeller 1 rotates around the support pin 7. . Here, the impeller 1 rotates by receiving a fluid from below. At this time, the impeller 1 slides upward and the upper end of the impeller 1 is pressed against the upper surface wall 6 and slides. Therefore, in the conventional impeller type flow meter, the auxiliary rectifying plate 4 is laid on the upper surface of the center rectifier 3 of the rectifier 2 as shown in FIG. To reduce the fluid pressure on the impeller 1 (for example, Patent Document 1).
[0003]
[Patent Document 1]
JP-A-9-145427 (paragraphs [0023] to [0028], FIG. 3)
[0004]
[Problems to be solved by the invention]
Incidentally, it is considered that the upward sliding of the impeller 1 affects the measurement performance. However, the above-mentioned conventional impeller type flow meter cannot satisfy the high measurement performance corresponding to the OIML (International Legal Metrology Organization) standard.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an impeller type flow meter and a rectifier capable of improving measurement accuracy compared to the related art.
[0006]
[Means for Solving the Problems]
A rectifier according to the invention of claim 1 made to achieve the above object is a rectifier arranged adjacent to a lower surface of an impeller among impeller flow meters that measure a flow rate based on rotation of the impeller. A tubular body that guides fluid to the impeller, a central rectifying body that is disposed near the impeller in the center of the cylindrical body and that supports the impeller, and that is inserted between the central rectifying body and the cylindrical body. It is characterized in that it comprises a plurality of rectifying walls provided and a weir portion projecting inward from a position below the central rectifying body on the inner surface of the cylindrical body and reducing the inner diameter of the cylindrical body.
[0007]
According to a second aspect of the invention, in the rectifier according to the first aspect, the area of a portion through which the fluid passes inside the weir portion is defined as A, and the portion of the cylindrical body through which the fluid passes through the open port on the impeller side. When the area is B, the ratio R obtained by R = A / B is 115 to 140%.
[0008]
According to a third aspect of the present invention, in the rectifier according to the first or second aspect, the weir portion is a flat ring fitted inside the cylindrical body.
[0009]
According to a fourth aspect of the present invention, in the rectifier according to any one of the first to third aspects, the plurality of rectifying walls are projected radially from the central rectifier, and the rectifying wall has a direction opposite to a rotation direction of the impeller. The facing surface is characterized in that an inclined surface is formed so that the straightening wall becomes thinner toward the end on the impeller side.
[0010]
According to a fifth aspect of the present invention, in the rectifier according to any one of the first to fourth aspects, the inclined surface is formed on a part of the rectifying walls of the plurality of rectifying walls and the other part of the rectifying walls. Is provided with a movable wing at an end on the impeller side, and the movable wing is characterized in that it is configured to be tiltable back and forth in the rotation direction of the impeller.
[0011]
According to a sixth aspect of the present invention, there is provided an impeller flow meter including the rectifier according to any one of the first to fifth aspects.
Function and effect of the present invention
When the impeller flow meter or the rectifier of the present invention is used, the fluid pressure on the impeller is appropriately suppressed by the weir portion, and the measurement accuracy can be improved as compared with the conventional impeller flow meter. Here, assuming that the area of the portion through which the fluid passes inside the weir portion is A, and the area of the portion of the cylinder through which the fluid passes at the open port on the impeller side is B, R = A / B , The ratio R is preferably 115 to 140% (the invention of claim 2). In addition, by forming the weir portion with a flat ring fitted inside the cylindrical body, the problem can be solved by an easy design change of fitting the ring to a conventional rectifier. 3 invention).
Furthermore, by forming an inclined surface that is inclined so that the rectifying wall becomes thinner toward the end on the impeller side, on the surface of the rectifying wall provided in the rectifier that faces in the direction opposite to the rotation direction of the impeller. The measurement accuracy can be further improved (the invention of claim 4). In addition, the inclined surface is formed on some of the rectifying walls, and movable wings are provided on the other rectifying walls at the end on the impeller side to improve measurement accuracy. Adjustment to make it possible.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The impeller flow meter 10 of the present invention (hereinafter, simply referred to as "flow meter 10") is obtained by assembling the flow meter main body 12 shown in FIG. 2 to an outer case 11 (see FIG. 1) attached in the middle of a water pipe. Become.
[0013]
In the outer case 11, an inlet 11A opened to the left and an outlet 11B opened to the right in FIG. 1 are formed, and a lower room 13 extending downward from the inlet 11A, An upper room 14 located above is provided. The upper room 14 and the lower room 13 communicate with each other in the up-down direction via the communication port 16. The flowmeter main body 12 is inserted and assembled into an upper surface opening 15 formed on the upper surface of the upper chamber 14, and the lower end of the flowmeter main body 12 is joined to the edge of the communication port 16.
[0014]
In the flow meter main body 12, reference numeral 50 in FIG. 2 denotes a cylindrical housing, and a pair of vertically arranged cylindrical portions 50A and 50B are connected by a plurality of ribs 52. The lower cylindrical portion 50B is opened up and down. The lower cylindrical portion 50B houses the blade 43 of the impeller 40, and the rectifier 20 is joined to the lower surface of the lower cylindrical portion 50B. ing. Then, as shown by the thick arrow in FIG. 1, the water flowing from the lower chamber 13 of the outer case 11 to the rectifier 20 and the lower cylindrical portion 50B in this order flows from the upper surface of the lower cylindrical portion 50B to between the ribs 52, 52. Pass through to the upper room 14 of the outer case 11 and to the outlet 11B.
[0015]
As shown in FIG. 2, a shaft receiving portion 53 hangs down from the lower surface of the upper cylindrical portion 50A so as to taper toward the center of the lower cylindrical portion 50B. A shaft 41 extending from the impeller 40 is housed.
[0016]
On the other hand, a meter unit 60 is mounted on the upper surface of the upper cylindrical portion 50A, and the meter unit 60 counts and displays the integrated flow rate of the water passing through the flow meter 10 in conjunction with the rotation of the impeller 40. When the upper lid 61 provided on the upper part of the meter unit 60 is opened, the flow rate display unit can be seen through the glass window 62.
[0017]
FIG. 3 shows only the impeller 40. As shown in the figure, the impeller 40 includes, for example, twelve blades 43 radially projecting from the outer peripheral surface of the cylindrical body 42. The upper edge 43A (downstream edge) of each blade 43 has a lower edge 43B (upstream edge) counterclockwise with respect to the upper edge 43A of each blade 43 when viewed from the downstream side in FIG. Prior to the surrounding direction, the entire blade 43 has a twisted shape. Thus, when water pressure is applied to the blade 43 from the upstream, the impeller 40 rotates so that the lower edge 43B of the blade 43 precedes. That is, the impeller 40 rotates counterclockwise as viewed from above.
[0018]
The shaft 41 rises vertically upward from the center of the bottom surface of the cylindrical body 42, and the space between the shaft 41 and the inner surface of the cylindrical body 42 is reinforced by a rib 46.
[0019]
As shown in FIG. 4, a cavity with an open lower end is formed in the core of the shaft 41, and a bearing 47 is attached to a position near the lower end in the hollow. Then, a support pin 21 provided in the rectifier 20 described later is inserted into the cavity from the lower end of the shaft 41, and the tip of the support pin 21 is abutted against the bearing 47.
[0020]
At the upper end of the shaft 41, one of the magnet couplings 44 is provided, and as shown in FIG. 2, the magnet coupling 44 is arranged to face the other magnet coupling 44 fixed to the gear 64 constituting the meter unit 60. Thereby, the rotation of the impeller 40 is transmitted as the rotation of the gear 64 of the meter unit 60.
[0021]
Further, a convex portion 48 is provided at the center of the upper end surface of the shaft 41, and a bearing member 49 is provided at a position of the meter unit 60 facing the convex portion 48 (FIG. 2). See).
[0022]
Now, as shown in FIG. 5, the rectifier 20 includes a central rectifier 22 according to the present invention in the center of the inside of a cylindrical cylinder 27, and for example, six rectifiers 22 from the central rectifier 22 toward the cylinder 27. The rectifying wall 70 has a structure extending radially.
[0023]
The cylindrical body 27 is opened up and down, and a slide ring 32 is attached to an upper end edge thereof. Specifically, elongated holes 35, 35 are formed at two places 180 ° apart from each other in the slide ring 32, and screws inserted into these elongated holes 35, 35 are screwed into the upper end of the cylindrical body 27. . By loosening the screw, the slide ring 32 can be turned on the cylinder 27, and the screw can be tightened at a desired position to fix the slide ring 32 to the cylinder 27. Further, lateral grooves 33, 33 that are open inward are formed at positions substantially 90 degrees apart from the long holes 35, 35.
[0024]
The central rectifier 22 is arranged at a position closer to the upper end (downstream end) of the cylindrical body 27. The center rectifier 22 has a dome shape that is open at the top surface and is rounded and tapered downward. The apex of the dome, that is, the lower end portion 22U of the central rectifier 22, reaches a substantially middle position in the axial direction of the cylindrical body 27, and the dome is provided with a shaft core portion 22A. A support pin 21 stands upward from the upper end of the shaft core portion 22A. The support pin 21 is inserted into the cavity of the shaft 41 as described above, and rotatably supports the impeller 40. Note that, for example, six ribs 26 extend radially from the shaft core portion 22A, and a rectifying wall 70 is formed on an extension of the ribs 26.
[0025]
The plurality of rectifying walls 70 are parallel to the axial direction of the cylindrical body 27 in the vertical direction. The lower end edge of the rectifying wall 70 is gradually inclined downward from the center rectifier 22 toward the cylindrical body 27, and the lower end edge 70 </ b> U of the rectifying wall 70 on the cylindrical body 27 side is aligned with the central rectifier 22. (See FIG. 4). As shown in FIG. 5, the movable wings 29 are provided on the two rectifying walls 70B opposed to each other among the plural (six) rectifying walls 70, and the movable wings 29 are provided on the remaining (four) rectifying walls 70A. Has an inclined surface 28.
[0026]
The rectifying wall 70B provided with the movable wing 29 has a concave portion 71 opened toward the impeller 40 in a portion near the cylindrical body 27. The movable wing 29 has a substantially rectangular flat plate shape corresponding to the recess 71 and is assembled in the recess 71. Specifically, a pin 34 inserted from the outer surface of the cylindrical body 27 is inserted into the lower end of the movable wing 29, and the movable wing 29 can be tilted about the pin 34. At the upper end of the movable wing 29, an emboss 30 is projected and engaged into the lateral grooves 33, 33 of the slide ring 32. Thus, the movable wings 29, 29 are symmetrically tilted with the rotation of the slide ring 32.
[0027]
The inclined surface 28 is formed on a surface of the flow regulating wall 70A that faces in a direction opposite to the rotation direction of the impeller 40 (the counterclockwise direction when viewed from above in FIG. 5). In the present embodiment, the inclined surface 28 is formed only on the impeller 40 side of the rectifying wall 70A, and portions other than the inclined surface 28 in the rectifying wall 70A are flat. The portion of the rectifying wall 70A on the impeller 40 side is configured such that the thickness of the rectifying wall 70A becomes gradually thinner toward the end near the impeller 40 due to the inclined surface 28.
[0028]
As shown in FIG. 4, the rectifier 20 is provided with a weir portion 80 that protrudes inward from a position below the central rectifier 22 on the inner surface of the cylindrical body 27. More specifically, the weir portion 80 is formed by fitting a flat ring to the cylindrical body 27 and fixing the ring to the lower end edge 70 </ b> U of the rectifying wall 70. Thereby, the weir portion 80 is disposed at a position upstream of the lower end portion 22 </ b> U of the central rectifier 22. The opening area of the cylindrical body 27 is reduced by the weir portion 80.
[0029]
Next, the operation of the present embodiment having the above configuration will be described.
As shown by the bold arrow in FIG. 1, the water flowing into the lower room 13 from the inlet 11A of the outer case 11 flows along the rectifying wall 70 (70A, 70B) of the rectifier 20 and flows to the impeller 40. Heading. Then, the impeller 40 receives the water guided by the flow regulating walls 70 (70 </ b> A, 70 </ b> B) with each blade 43 and rotates. The water that has passed through the impeller 40 flows out from between the ribs 52 of the cylindrical housing 50 to the side of the flowmeter main body 12, and flows toward the outlet 11 </ b> B through the upper chamber 14 of the outer case 11. The rotation of the impeller 40 is transmitted to the meter unit 60 via the magnet couplings 44, 44, and the flow rate of water is measured and displayed.
[0030]
<Experiment 1>
The following experiment was conducted in order to investigate the effect of the "weir section 80" according to the present invention. The experimental procedure is as follows.
{Circle around (1)} Water flows at a preset flow rate through the flow meter 10 of the present invention having the rectifier 20 having the weir portion 80 and the conventional flow meter having the rectifier not having the weir portion 80. The thrust load applied to the impeller of each flow meter at the set flow rate value was determined.
{Circle around (2)} The experimental results were graphed as shown in FIG.
[0031]
In addition, each flow meter is provided with a movable blade 29, and in this experiment, each movable blade 29 is set substantially vertical.
[0032]
Comparing the flow meter 10 of the present invention with the conventional flow meter based on the graph of FIG. 6, the thrust load of the flow meter 10 of the present invention is equal to the thrust load of the conventional flow meter at any set flow rate value. It is a smaller value. From this, it was found that forming the weir portion 80 in the rectifier 20 reduced the thrust load applied to the impeller 40.
[0033]
<Experiment 2>
Next, the thrust based on the ratio A / B of the ratio of the flow area A (see FIG. 12) of the portion surrounded by the weir portion 80 to the flow area (flow area) B of the fluid at the opening of the cylindrical body 27 on the impeller 40 side. The following experiment was conducted to examine the difference in load reduction effect. The procedure of the experiment is the same as that of Experiment 1 except that the ratio A / B was set to 115%, 125%, and 140%. Therefore, the description is omitted.
[0034]
As shown in the graph of FIG. 7, at any set flow rate value, the value of the thrust load decreases as the ratio A / B decreases. From this, it is understood that the effect of reducing the thrust load increases as the amount of protrusion of the weir 80 toward the inside of the cylindrical body 27 increases and the flow area A of the portion surrounded by the weir 80 decreases.
[0035]
<Experiment 3>
Next, an experiment was conducted to examine the adaptability of the flow meter of the present invention to the OIML standard. The experimental procedure is as follows.
{Circle around (1)} Water is passed at a preset flow rate between the flow meter 10 of the present invention having the rectifier 20 having the weir portion 80 and the flow meter having the conventional rectifier having no weir portion 80, and The measured value of each flow meter at the set flow rate value was obtained.
{Circle around (2)} The instrumental difference of each flow meter was calculated for each set flow rate and graphed (instrumental difference curve).
[0036]
Here, “instrument difference” is obtained by the following equation, where X is the weighing value and Y is the true value.
Instrumental difference (%) = ((X−Y) / Y) · 100
[0037]
The experimental result is shown in FIG. 8, in which the instrument curve of the flow meter 10 of the present invention is represented by a broken line, and the instrument curve of the conventional flow meter is represented by a solid line.
[0038]
As shown in FIG. 8, the instrumental difference peak of the flow meter 10 of the present invention is smaller than the instrumental difference peak of the conventional flow meter over almost the entire set flow rate value (Q1 to Q4 in FIG. 8). . From this, it was found that the flow meter of the present invention had better accuracy than the conventional flow meter.
[0039]
Further, the instrumental error tolerance range based on the OIML standard enclosed by the thick line in FIG. 8 (the instrumental error between the set flow rate values Q2 and Q3 is within ± 5%, and the instrumental error between the set flow rate values Q3 and Q4 is ± 2 %), The conventional flow meter is out of the allowable range in the small flow rate range, whereas the flow meter 10 of the present invention is in the allowable range in the entire range from the small flow rate range to the large flow rate range. It fits in. From this, it has been found that the flow meter 10 of the present invention conforms to the OIML standard and can measure with high accuracy from a small flow rate range to a large flow rate range.
[0040]
<Other embodiments>
The present invention is not limited to the above-described embodiments. For example, the following embodiments are also included in the technical scope of the present invention, and furthermore, various embodiments may be made without departing from the spirit of the present invention. It can be changed and implemented.
(1) In the above-described embodiment, the weir portion 80 is provided below (upstream) the lower end edge 70U of the rectifying wall 70, but at a position lower than the lower end portion 22U of the central rectifier 22. If so, the position is not limited to this position. For example, as shown in FIG. 9, the weir portion 100 may be provided at a position above the lower end edge 70U of the rectifying wall 70. Even with such a configuration, an effect equivalent to that of the above-described embodiment can be obtained.
[0041]
(2) In the above-described embodiment, the weir portion 80 has an annular shape. However, as shown in FIG. 10, a configuration in which a plurality of arc-shaped weir portions 110 are provided at predetermined intervals may be employed. Even with such a configuration, an effect equivalent to that of the above-described embodiment can be obtained.
[0042]
(3) In the above embodiment, the inner peripheral surface of the weir portion 80 is parallel to the axial direction of the cylindrical body 27. However, as in the weir portion 120 shown in FIG. It may be tapered so that the inside diameter is small.
[Brief description of the drawings]
1 is a sectional view of a flow meter according to an embodiment of the present invention; FIG. 2 is a sectional view of a flow meter main body; FIG. 3 is a perspective view of an impeller; FIG. 4 is a sectional view of a rectifier and an impeller; FIG. 6 is a graph showing the results of experiment 1 FIG. 7 is a graph showing the results of experiment 2 FIG. 8 is a graph showing the results of experiment 3 FIG. 9 is another embodiment ( FIG. 10 is a bottom view of a rectifier according to another embodiment (2). FIG. 11 is a side sectional view of a rectifier wall according to another embodiment (3). FIG. 13 is a conceptual diagram showing the flow area of the enclosed portion and the flow area at the opening of the cylindrical body on the impeller side. FIG. 13 is a cross-sectional view of a conventional flow meter. FIG. 14 is a cross-sectional view of a conventional rectifier.
10 impeller flow meter 20 rectifier 22 central rectifier 27 cylindrical body 40 impellers 80, 100, 110, 120 dam

Claims (6)

A rectifier arranged adjacent to the lower surface of the impeller among the impeller flow meters that measure the flow rate based on the rotation of the impeller,
A cylindrical body that guides fluid to the impeller, a central rectifier that is disposed near the impeller and that supports the impeller in a central portion of the cylindrical body, and a central rectifier and the cylindrical body A plurality of rectifying walls interposed therebetween, and a weir portion that protrudes inward from a position below the central rectifying body on the inner surface of the cylindrical body and reduces the inner diameter of the cylindrical body. Rectifier characterized. When the area of the portion through which the fluid passes inside the weir portion is A, and the area of the portion through which the fluid passes at the open port on the impeller side of the cylindrical body is B,
R = A / B
The rectifier according to claim 1, wherein the ratio R obtained in the step (1) is 115 to 140%. The rectifier according to claim 1, wherein the weir is a flat ring fitted inside the cylindrical body. The plurality of straightening walls are radially extended from the central straightening body,
On the surface of the flow regulating wall facing in the direction opposite to the rotation direction of the impeller, an inclined surface that is inclined so that the flow regulating wall becomes thinner toward an end on the impeller side is formed. The rectifier according to any one of claims 1 to 3, wherein: The inclined surface is formed on a part of the rectifying walls of the plurality of rectifying walls, and a movable wing is provided on an end of the other rectifying wall on the impeller side; The rectifier according to any one of claims 1 to 4, wherein the rectifier is configured to be capable of tilting back and forth in the rotation direction of the impeller. An impeller type flow meter comprising the rectifier according to any one of claims 1 to 5.

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