JP2013024770A - Tangential flow impeller type water meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an instrument error to be within the verification tolerance range of a tightened new measurement method by securing the flatness of the instrument error with improvement of the shape of an impeller.SOLUTION: A tangential flow impeller type water meter includes: a lower case Dwhose inner part is a measurement chamber M; an impeller A where multiple plate-like blades Pare integrally arranged in a shaft part 5 in a radiation direction, and which is arranged in the measurement chamber M of the lower case Dso as to be rotatable via a pivot 4; a display mechanism for displaying an integrated passage amount of a water flow passing through the measurement chamber M of the lower case D; and an upper case Dwith a hinge opening/closing structure for clogging the upper surface opening of the lower case D. Round surface chamfering Cis obtained over the whole height of a side which is the distal end of each of the blades Pconstituting the impeller A and is a rear surface with respect to the water flow.

Description

  The present invention relates to a tangential flow impeller-type water meter that measures an accumulated passing amount of a passing water flow by rotating the impeller by a tangential flow of the water flow flowing into a measuring chamber.

  The tangential flow impeller water meter (hereinafter sometimes simply referred to as “water meter”) has a measuring chamber inside, and has one inlet and one outlet connected to the measuring chamber. A lower case formed on the shaft, a plurality of flat blade blades integrally provided in the radial direction on the shaft, and rotatably disposed in a weighing chamber of the lower case via a pivot; It is arranged in the space above the measuring chamber in the case, and the rotation of the impeller rotated by colliding the water flow flowing into the measuring chamber from the inlet into a tangential flow with each blade plate is reduced. And a display mechanism for displaying the accumulated passage amount of the water flow and an upper case of a hinge opening / closing structure for closing the upper surface opening of the lower case.

  And in the conventional water meter, the change of the instrumental error in the entire flow rate range is reduced as much as possible, i.e., the flatness of the instrumental error is secured, and the instrumental error is within the verification tolerance range defined by the Measurement Law. By finely adjusting the position of the adjuster or resistor placed in the weighing chamber of the lower case, the water flow path can be changed slightly, or the resistance to the water flow can be changed slightly. Has realized.

However, under the new measurement law that came into effect on April 1, 2011, the rated minimum flow rate (Q ₁ ) is smaller than before, and the instrumental error shifts from ± 5% to ± 2%. Since the flow rate (Q ₂ ) is set to 1.6 times the rated minimum flow rate (Q ₁ ) (Q ₂ = Q ₁ × 1.6), the transfer flow rate (Q ₂ ) becomes smaller than before. As a result, the tolerance for testing became stricter.

  In this way, since the test tolerance has become stricter in the new measurement method, the flatness of the instrumental error can be improved and the instrumental error within the verification tolerance range only by fine adjustment using the regulator and resistor alone or in combination. It became difficult to fit.

JP-A-7-270201

  An object of the present invention is to improve the flatness of the instrumental error by improving the shape of the impeller so that the instrumental error falls within the strict tolerance range of the new measurement method.

  The invention of claim 1 for solving the above-mentioned problem is characterized in that the inside is a measuring chamber, the lower case provided with one inflow port and one outflow port connected to the measuring chamber, and the shaft portion. A plurality of flat blades are integrally provided in the radial direction, arranged in a space above the weighing chamber in the lower case, and an impeller arranged rotatably in the weighing chamber of the lower case via a pivot. The flow of water flowing into the measuring chamber from the inlet becomes a tangential flow to each blade and collides and rotates the impeller to decelerate and display the accumulated passage amount of the water flow A tangential flow impeller-type water meter provided with a display mechanism to be closed and an upper case of a hinge opening / closing structure for closing an upper surface opening of the lower case, and at a tip portion of each blade plate constituting the impeller There is an arc on the back side against the water flow. Chamfering is characterized in that it is applied over the entire height.

  Since the rotational speed of the impeller (the peripheral speed at the tip of the blade) is designed to be slower than the flow velocity of the water flowing from the inlet of the lower case, the water flows press the front surface of each blade. In form, the impeller is rotated. In addition, in a tangential flow impeller type water meter, the change in instrumental difference with respect to the flow rate increases from the rated minimum flow rate to the specified flow rate, and the instrumental difference gradually increases from the specified flow rate to the rated maximum flow rate. It is known that the instrumental difference is substantially constant at a flow rate that drops and is greater than about 200 (L / h). Therefore, it is also known that in a flow rate region greater than about 200 (L / h), the instrumental difference is negative and the value itself is the largest.

  In a tangential flow impeller-type water meter, a pressing force due to a water flow sequentially acts on the front surface of the impeller facing the inlet among the impellers of the impeller, and the impeller is rotated by the pressing force. For this reason, the water accommodated in the space between the remaining blade plates adjacent to each other excluding the space surrounded by the blade plate facing the inlet and the blade plate adjacent to and adjacent to the blade plate, It has some inertia and has the effect of being rotated by the rotation of the impeller. In a water meter, a phenomenon occurs in which water flows in a direction opposite to the rotational direction of the impeller relatively in the gap between the inner peripheral surface of the measurement chamber of the lower case and the tip surface of each blade, and the conventional water meter Then, since the front end portion of each impeller blade of the impeller is formed at a right angle in cross-sectional view, when the flow rate increases, the gap and the rear side of the front end portion of the impeller blade In this case, a water flow having an irregular flow or a vortex may be generated.

  Since the water flow or vortex flow having an irregular flow described above acts as a resistance to the rotation of the impeller, it causes the instrumental error to be reduced in a region where the flow rate is large. As mentioned above, as described above, in the flow rate region larger than about 200 (L / h), the instrumental error becomes negative, and the value itself is considered to be the largest.

  In the first aspect of the present invention, since the chamfer is chamfered over the entire height at the tip of each blade plate constituting the impeller and on the side that becomes the back surface with respect to the water flow, it is pressed by the water flow. The front side of the slats maintains a flat surface up to the tip, and the water flow on the back side of the tip of the slats is maintained while maintaining the state in which the pressing force by the water stream acts in the same way as a conventional impeller. Smooth the flow. That is, by rounding the back side of the tip of each impeller of the impeller, the “drag coefficient” indicating the degree of resistance to water flow is reduced, and the degree of the “drag coefficient” is reduced as the water flow is faster. Increased in high Reynolds number range. As a result, when the water flow is fast, chamfering on the back side of the tip of the blade plate has a great effect, further reducing the “drag coefficient” and facilitating the rotation of the impeller.

  For this reason, according to the invention of claim 1, the ratio of the integrated rotational speed of the impeller to the integrated passage amount of the water flow is increased, and the instrumental difference is positive in the entire flow rate range. The degree increases at high flow rates. As a result, the flatness of the instrumental error is ensured, and it becomes possible to cope with the new standard of the instrumental error based on the new measurement law, which has become a tighter test tolerance.

  The invention of claim 2 is the invention of claim 1, wherein the width of the tip of the blade is (1-3) mm, and the radius of the chamfer is the width of the tip of the blade ( 0.3 to 1.0).

  According to invention of Claim 2, since the part where the rounded chamfering is given to the front-end | tip part of a slat is 30% or more of the width | variety of the front-end | tip part of the said slat, the water flow of the back side of the said slat The effect of smoothing is increased.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, a portion that is a front surface with respect to a water flow at a tip portion of the vane plate is chamfered.

  According to the invention of claim 3, in addition to the chamfering being performed on the back side of the front end portion of the blade plate, the front surface side of the front end portion of the blade plate is chamfered. Therefore, the flow of the water flow on the front side of the blade plate between the inner peripheral surface of the measuring chamber and the tip surface of the blade plate becomes smooth, which contributes to the flattening of the instrumental error.

  According to the present invention, by rounding the back side of the tip of each impeller of the impeller, the “drag coefficient” indicating the degree of resistance to water flow is reduced, and the degree to which the “drag coefficient” is reduced is small. When the water flow is fast, the chamfer on the back side of the tip of the slats has a great effect, and the “drag coefficient” is further reduced. It becomes easier to rotate the impeller, and the ratio of the cumulative rotational speed of the impeller to the cumulative passage amount of the water flow increases, and the instrumental difference is positive in the entire flow rate range. It becomes larger in the high flow rate region. As a result, the flatness of the instrumental error is ensured, and it becomes possible to cope with the new standard of the instrumental error based on the new measurement law, which has become a tighter test tolerance.

It is a longitudinal section of a single box type tangential flow impeller water meter provided with impeller A concerning the present invention. It is the XX sectional view taken on the line of FIG. 1 is a perspective view of an impeller A. FIG. (B) and (b) show the flow of water flow between the tip surface of the impeller P ₁ of the impeller A of the present invention and the impeller plate P ′ of the conventional machine structure and the inner peripheral surface of the measuring chamber M, respectively. It is the elements on larger scale shown in the main body (magnified figure of the part of E of Drawing 2). It is a graph which compares and shows the instrumental difference with respect to the flow volume of the water meter which concerns on this invention, and the conventional water meter. (A), (b) is an enlarged section of the tip of blades P ₂ and P _{3 having} different ratios of radius (R) of radius chamfering C ₂ and C ₃ to the width (W) of the blade tip. FIG.

  Hereinafter, the present invention will be described in more detail with reference to the best examples of the present invention.

1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a single box type tangential flow impeller water meter provided with an impeller A according to the present invention, and FIG. 2 is a sectional view taken along the line XX of FIG. is a perspective view of the impeller a, FIG. 4 (a), (b) has a front end surface of the blade plate P 'of the blade plate P ₁ and the conventional device structure of the impeller a of the present invention, respectively, the measuring chamber It is the elements on larger scale which mainly show the flow of the water flow between the internal peripheral surfaces of M (enlarged figure of the part of E of FIG. 2). The lower case D ₁ has a measuring chamber M having a hollow short cylindrical shape in the lower half in the height direction inside, and an inlet 1 and an outlet 2 connected to the measuring chamber M are provided at the lower end. I have. A strainer 3 is disposed in the inflow port 1. The impeller A is disposed in the measuring chamber M of the lower case D ₁ and is rotatably supported via the pivot 4. The pivot 4 is integrally inserted into the shaft portion 5 of the impeller A, and a pivot support 6 and a pivot nut 7 are attached to a lower end portion of the pivot 4. The pivot support 6 and the pivot nut 7 are The impeller A is housed in a recessed portion 9 formed at the center of the bottom wall portion 8 of the lower case D ₁ , and the impeller A is rotatably set on the bottom wall portion 8 of the lower case D ₁ via the pivot 4.

A register box B is fitted into the upper half of the inner space of the lower case D ₁ using a stepped portion, and the upper end portion of the shaft portion 5 of the impeller A is formed at the central portion of the lower surface of the register box B. It has entered the recess 11. In the register box B, a gear train for transmitting the rotation of the impeller A and rotating it at a reduced speed is arranged. The shaft portion 5 of the impeller A and the gear 12 arranged on the same axial center as the shaft portion 5 constituting the gear train are respectively connected to the shaft portion 5 and the gear 12. The magnets 13 and 14 are connected to each other through a magnet coupling. In FIG. 1, 15 is an intermediate gear constituting the gear train. The number wheel 17 is rotated by the rotation reduced through the gear train.

A glass plate 21 through which an indicator (not shown) attached to a specific gear constituting the gear train and the number wheel 17 can be seen through is fitted into the opening of the upper surface of the register box B through an O-ring 22. The upper case D ₂ is screwed into the outer side of the upper end portion of the lower case D ₁ . A ring-shaped pressing portion 23 is integrally provided at the upper end portion of the upper case D ₂ , and the peripheral edge portion of the glass plate 21 is pressed by the ring-shaped pressing portion 23 through a gasket 24. The upper case D _2, the lid 25 for closing the opening of the upper case D ₂ is opened and closed linked with the pin 26 as the fulcrum. In FIG. 1, 27 a and 27 b indicate a pair of adjusters arranged in an upper space by the blade plate P ₁ of the impeller A in the measuring chamber M for adjusting the instrumental error.

As shown in FIGS. 1 to 4, the impeller A includes a plurality of (six in the embodiment) blade plates P ₁ at equal intervals in the circumferential direction via a connecting portion 31 at a lower portion of the shaft portion 5. And are integrally formed along the radial direction. Each vane plate P ₁ is integrally formed with the shaft portion 5 via the connecting portion 31 in a portion slightly above the center portion in the height direction, and the upper end surface of the connecting portion 31 is the vane plate P _1. The first step portion 32 is formed between the upper end surfaces of the two and the lower end surface of the connecting portion 31 is positioned higher than the lower end surface of the blade plate P _1. Thus, a second stepped portion 33 larger than the first stepped portion 32 is formed between the two.

Width of the blade plate P ₁ is they become gradually narrower toward the base end to the tip, whereas the width W of the end portion is 2 mm, width of the proximal end is 3 mm. The height of the slats P ₁ is not constant throughout from the proximal end to the distal end, it is 11 mm. A round chamfering C ₁ and a flat chamfering C ₀ are applied to the tip of the blade plate P _{1 on} the side that becomes the back surface and the front surface with respect to the water flow. The radius of the round chamfer C ₁ is half (W / 2) of the width W of the tip of the blade plate P ₁ , and the length of one side of the flat plate C ₀ is the width of the tip of the blade plate P _1. It is 1/4 of W (W / 4).

Then, the water flowing in from the inlet 1 lower case D ₁ in the interior of the metering chamber M, and sequentially colliding become tangential flow against the vane plates P ₁ of the impeller A, the impeller A is When the impeller A is rotated, the gear train constituting the display mechanism and the number wheel 17 are rotated, and the accumulated passage amount of the water flow passing through the measuring chamber M is displayed. Incidentally, in FIG. 4, F indicates the force water flow acting on the vane plate P _1.

As described above, in the gap 34 between the inner circumferential surface Ma of the measuring chamber M of the lower case D ₁ and the tip surface of each blade plate P ₁ , water flows relatively in the direction opposite to the rotational direction of the impeller. In the water meter according to the present invention, the tip of each vane plate P ₁ of the impeller A has a rounded chamfered C ₁ on the back side and a flat chamfered C ₀ on the front side. Compared with an impeller having a blade P ′ in which both the front surface and the back surface of the section are formed at right angles in a sectional view, the water flow on the back surface side of each blade plate P ₁ and the portion of the gap 34 is smooth. Become. The “drag coefficient” representing the degree of resistance of the object to the water flow is smaller in the case where the object has a roundness than the case where the corner of the object has a corner with respect to the water flow, and It is known in the field of fluid dynamics that the degree of the “drag coefficient” is small in the high Reynolds number region where the water flow is fast, and the present invention utilizes this principle.

For this reason, when the impeller A having the blade plate P ₁ whose rear surface side is rounded chamfered C ₁ is used, the resistance of each blade plate P ₁ of the blade wheel A to the water flow becomes small. In addition to the fact that the ratio of the integrated rotational speed of the impeller A to the integrated passage amount becomes large and the instrumental error becomes positive in the entire flow rate region, the degree to which the resistance to the water flow becomes small is high. As a result of the increase in the flow rate region, the degree to which the instrumental difference becomes positive becomes larger in the high flow rate region, and the instrumental error is flattened as a whole. The planar-up C ₀ on the front side of the distal end portion of the blade plate P ₁ is the flow on the front side of the portion of the tip portion of the blade plate P ₁ in the water flow smoothly, reducing the resistance of the blade plate P ₁ for water flow To contribute to.

FIG. 5 is a graph showing the difference between the water meter according to the present invention and the flow rate of the conventional water meter in comparison. In FIG. 5, the range surrounded by the thick line indicates the test tolerance range under the revised metrology law in which the transition flow rate (Q ₂ ) is smaller than the conventional one, and the curves indicated by the solid line and the broken line are the present invention. a water meter impeller a is incorporated with the blade plate P ₁ according to the respective instrumental error of the water meter of conventional impeller incorporated shown. FIG. 5 shows a water meter in which an impeller A having a blade plate P _{1 according} to the present invention is incorporated in a conventional water meter in which an impeller having a blade plate having a corner on the back side of the tip portion is incorporated. In comparison, the resistance of the tip of the slats with respect to the water flow becomes small, so that the instrumental error becomes positive in the entire flow rate region, and the resistance of the slats with respect to the water flow becomes small in the high flow rate region. In addition, it can be seen that the instrumental error is flattened by increasing the degree to which the instrumental error becomes positive, and the instrumental error in the entire flow rate range falls within the verification tolerance range under the revised measurement law.

In addition, regarding the rounded chamfer formed on the back side of the tip of the impeller blade plate, the radius (R) of the rounded chamfer with respect to the width (W) of the tip of the blade plate is R = (0.3 to 1.0). ) It is appropriately determined within the range of × W. 6 (a) and 6 (b) show the tip portions of the blade plates P ₂ and P _{3 having} different ratios of the radius (R) of the rounded chamfers C ₂ and C ₃ to the width (W) of the blade blade tip portion, respectively. It is an expanded sectional view. In general, it is considered that the greater the (R / W) ratio, the smaller the resistance of the vane against water flow. Incidentally, the width of the tip portion of the blade plate P ₁ to P ₃ is selected in the range of (1 to 3) mm.

  In the above embodiment, the pivot 4 that supports the impeller A and the input side gear that constitutes the gear train are connected by a magnet coupling, but the gear is connected to the upper end of the shaft portion. The present invention can also be implemented for an impeller in which input side gears constituting a row are integrally formed.

A: impeller C ₁ -C _3: radiusing
C ₀ : Flat surface
D ₁ : Lower case
D ₂ : Upper case
M: measuring chamber P ₁ ~P _3: slats
W: Width of the tip of the blade
1: Inlet
2: Outlet
4: Pivot
5: Shaft of impeller 12, 15: Gear (display mechanism)
17: Number wheel (display mechanism)

Claims (3)

A lower case in which the inside is a weighing chamber, and each has one inlet and one outlet connected to the weighing chamber;
A plurality of flat blade plates are integrally provided in the radial direction on the shaft portion, and an impeller disposed rotatably in the weighing chamber of the lower case via a pivot;
The rotation of the impeller, which is arranged in the space above the measuring chamber in the lower case and is rotated by colliding with the water flow flowing into the measuring chamber from the inflow port as a tangential flow with each blade, is reduced. A display mechanism for displaying the accumulated passage amount of the water flow,
An upper case of a hinge opening and closing structure for closing an upper surface opening of the lower case;
A tangential flow impeller water meter with
A tangential flow impeller-type water meter, which is a tip portion of each impeller constituting the impeller and is chamfered over the entire height on a side that is a back surface with respect to the water flow.   The width of the tip of the blade is (1-3) mm, and the radius of the rounded chamfer is in the range of (0.3-1.0) of the width of the tip of the blade. The tangential flow impeller-type water meter according to claim 1, wherein   The tangential flow impeller-type water meter according to claim 1 or 2, wherein a portion of the front end portion of the blade plate that is a front surface with respect to the water flow is flattened.

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