JP2896999B2 - Impeller of impeller type flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller used in an impeller type flow meter such as a vertical Waltmann water meter.

[0002]

2. Description of the Related Art FIGS. 6 and 7 illustrate a conventional impeller used in a vertical Wartmann water meter, which is an example of an impeller flow meter. This impeller 10
A large-diameter body 12 is provided concentrically on a rotating shaft 11, and a large number of blades 13 inclined with respect to the axis of the rotating shaft 11 are provided on the body 12 at intervals. 13 has four corner portions 13a, 13b,
A rectangular fluid receiving surface 14 (see FIG. 6) in which each of 13c and 13d forms a right angle is provided. 6 and 7 show only one blade 13, and other blades are not shown for convenience of description.

In a vertical Waltmann water meter employing the impeller 10 described with reference to FIG.
Each of the fluid receiving surfaces 14 of the plurality of blades 13 receives the force of the water flow to rotate the impeller 10 together with the rotating shaft 11 around the axis, and the rotation of the impeller 10 per unit time The flow rate is measured by the quantity.

[0004] The performance of a water meter is generally represented by its performance curve. This performance curve plots the flow rate on the horizontal axis and the instrumental error on the vertical axis, and compares the measured value at each flow rate from the small flow rate range to the large flow rate range with the ideal performance and expresses it as the instrumental error. It is. In FIG. 5, the ideal performance A is represented by a broken line with respect to the performance of the water meter, and the performance of a vertical Waltmann water meter employing the impeller 10 having the structure described with reference to FIG. . Ideal performance A
Is a straight line A where the instrumental error is “0” regardless of the change in the flow rate
Represented by On the other hand, the performance curve of the vertical Wartmann water meter employing the conventional impeller (conventional product) described with reference to FIG. 10 shows that in a large flow rate region, the impeller receives the reaction torque T2 due to the resistance of the fluid. In a small flow rate range (fine flow rate range), the impeller has a mechanical resistance torque T due to bearing friction.
The performance curve (characteristic curve)
And a large peak value P2 appears in the micro flow rate region.

Therefore, in the conventional impeller, the number of blades is designed to be 12 or the like so as to secure the instrumental difference performance in a small flow rate region. However, in such a case, the number of blades is large. The resistance torque T2 due to the water flow resistance increases, so that the rotation speed of the impeller in the large flow rate region is limited, and as a result, a characteristic curve in which the peak value P2 increases is drawn.

[0006] The fact that the peak value is large has been a weak point of the vertical Waltmann water meter.

[0007]

The present invention focuses on this point, and by devising the impeller blade shape, it is possible to reduce the reaction torque due to the resistance of the fluid and to reduce the peak value to a small value. The purpose is to provide.

[0008]

SUMMARY OF THE INVENTION An impeller of an impeller type flow meter according to the present invention has an impeller in which a number of impellers are provided around a rotating shaft and inclined with respect to the axis of the rotating shaft. Is an impeller of an impeller type flow meter disposed in a fluid passage, wherein the impeller has a substantially rectangular fluid receiving surface and is located on the fluid receiving surface on the downstream side in the fluid flow direction. A right-angled corner portion to be formed by the rear side to be formed and the outer side of the fluid receiving surface is omitted, and the contour of a continuous portion between the rear side and the outer side is formed in an arc shape. That is.

[0009] In the impeller, the corner portion may be omitted with respect to the area of the fluid receiving surface when a right-angled corner portion to be formed by the rear side and the outer side is not omitted. It is practically desirable that the area of the exclusion range in this case be 0.2 to 8.0%. Further, it is desirable for practical use that the radius of the arc-shaped contour line is 2 to 3 mm.

According to such an impeller, since the contour of the continuous portion between the rear side and the outer side of the fluid receiving surface of the blade is formed in an arc shape, the reaction torque due to the resistance of the fluid is reduced. Therefore, the peak value can be kept small. Another impeller of the impeller type flow meter according to the present invention has an impeller in which a number of blades which are provided around a rotation axis and are inclined with respect to the axis of the rotation axis are provided at intervals in a fluid passage. The impeller of the impeller type flowmeter, wherein the impeller has a fluid receiving surface, and a rear end located on the inner side of the fluid receiving surface on the downstream side in the fluid flow direction and the fluid receiving surface. The rear end of the outer side of the surface is continuous with a side having a convex arc-shaped contour line having a radius of the same dimension as the width dimension of the fluid receiving surface in the radial direction of the rotation axis. is there.

Also in this impeller, a rear end located on the downstream side in the fluid flow direction on the inner side of the fluid receiving surface provided on the impeller and a rear end of the outer side on the fluid receiving surface are:
By being continued by the side having a convex arc-shaped contour line having a radius of the same dimension as the width dimension of the fluid receiving surface in the radial direction of the rotating shaft, the resistance torque due to fluid resistance decreases, The peak value can be kept small.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view of an upright Waltmann water meter employing an impeller 1 according to the present invention, in which a main part is cut away. In the figure, an impeller 1 is mounted rotatably about a vertical axis. A rectifier 6 and an impeller housing case 5 provided above the rectifier 6 and surrounding the impeller 1 are assembled to the case 7 of the water meter. The impeller 1 rotates by receiving the force of the water flow passing through the fluid passage 8 formed by the rectifier 6 and the impeller housing case 5 at the fluid receiving surface 41 (see FIG. 2: described later) of the impeller 4. The shaft 3 is rotated around its axis. In FIG. 1,
The arrows indicate the flow direction of the water flow.

FIG. 3 illustrates the impeller 1 described above. In the impeller 1, a large diameter body 2 is provided concentrically on a rotating shaft 3, and a large number of blades 4 inclined with respect to the axis of the rotating shaft 3 are provided on the body 2 at intervals. Each of the blades 4 is provided with the fluid receiving surface 41 having a substantially rectangular shape. FIG. 2 shows only one blade 4 for explanation, and other blades are not shown for convenience of explanation. In this impeller 1, the water flow flows as indicated by an arrow F1. And regarding the fluid receiving surface 41 of the blade 4,
A right-angled corner portion 4 to be formed by the rear side 42 and the outer side 43 located downstream in the flow direction F1 of the water flow.
1c is omitted, and a contour 44 of a continuous portion of the rear side 42 and the outer side 43 is formed in an arc shape. The other three corner portions 41a, 41b, 41d of the fluid receiving surface 41 are formed at right angles. Therefore, this impeller 1 is different from the conventional impeller 10 described with reference to FIGS. 6 and 7 in that the rear side 42 of the fluid receiving surface 41 located downstream in the flow direction F1 of the water flow and the fluid receiving surface thereof A point that a right angle corner portion 41c to be formed by the outer side 43 in 41 is omitted, and a contour 44 of a continuous portion of the rear side 42 and the outer side 43 is formed in an arc shape. Only.

The shape of the fluid receiving surface 41 of the blade 4 is, as shown in FIGS.
Rear end 4 located on the downstream side in the fluid flow direction F1 at
5a and the rear end 43 of the outer side 43 of the fluid receiving surface 41
a may be continuous with a side 46 having a convex arc-shaped contour line having a radius R2 of the same dimension as the width dimension W of the fluid receiving surface 41 in the radial direction of the rotating shaft 3. The other three corner portions 41a, 41 of the fluid receiving surface 41
b and 41d are each formed at right angles. Therefore, in the impeller 1 of FIGS. 3 and 4, the radius R1 of the contour 44 of the fluid receiving surface 41 described in FIG. It is possible to grasp.

The performance curve of a vertical type Waltmann water meter incorporating the impeller 1 (invention product: the number of blades is 12 same as the conventional product) described in FIG. 2 is adopted for the conventional product. In contrast to the performance curve C of the vertical Waltmann water meter, it is shown by a solid line B in FIG. According to this water meter, the resistance torque T1 due to the resistance of the water flow in the large flow area.
However, the reaction torque T2 in the case of using the conventional product was reduced, and the peak value P1 in the minute flow rate region was accordingly reduced. In particular, the shape of the rear end 41 of the blade 4 is shown in FIGS.
It has been confirmed that the peak value P1 in the minute flow rate region is extremely small in the freshly-worn Waltmann water meter incorporating the impeller 1 having the shape described in (1). In addition, the minus part from the ideal performance A of the reaction torque T1 for the invention shown in FIG. 5 is corrected by using the gear mechanism adopted in the flow rate display mechanism of the vertical Waltmann water meter. By doing so, the performance curve B of the invention can be made closer to the ideal performance A.

The same operation as described above is exhibited by adopting the impeller according to the present invention not only in the vertical type Waltmann water meter but also in other types of water meters and other impeller flow meters. Is done.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the impeller 1 described with reference to FIG. 2, a right-angled corner portion (indicated by a dashed line) 41c to be formed by a rear side 42 and an outer side 43 of a fluid receiving surface 41 is omitted. Investigation of the preferred area of the missing area A when the corner portion 51c was omitted with respect to the area of the fluid receiving surface 41 when there was no
It was confirmed that when the area was 0.2 to 8.0%, the peak value P1 shown in FIG. 5 was extremely small. When the area of the exclusion range A is smaller than 0.2%, the resistance torque T1 due to the resistance of the water flow in the large flow rate area does not decrease so much as compared with the resistance torque T2 when the conventional product is used.
This tended to prevent the peak value P1 from decreasing in the micro flow rate range. When the area of the deletion range A is larger than 8.0%, the effect of the mechanical resistance torque T due to the bearing friction in the micro flow rate region tends to be large.

In the impeller 1 described with reference to FIG.
The radius of the arc-shaped contour line 44 on the fluid receiving surface 41 is set to 2
It has been confirmed that when the distance is set to 3 mm, the peak value P1 shown in FIG. 5 becomes extremely small. When the radius of the contour line 44 is smaller than 2 mm, the reaction torque T1 due to the resistance of the water flow in the large flow rate region is larger than the reaction torque T2 when the conventional product is used.
, And there was a tendency that the peak value P1 in the micro flow rate region was prevented from decreasing. When the radius of the contour line 44 is larger than 3 mm, the effect of the mechanical resistance torque T due to the bearing friction in the minute flow rate range tends to appear.

[0019]

According to the present invention, it is possible to provide an impeller capable of reducing the reaction torque due to the resistance of the fluid and suppressing the peak value in the minute flow rate region. In particular, it is economical because only the blade shape of the impeller needs to be changed.

[Brief description of the drawings]

FIG. 1 is a cutaway side view of a vertical Waltmann water meter employing an impeller of the present invention.

FIG. 2 is an explanatory view partially showing an impeller of the embodiment according to the present invention.

FIG. 3 is a perspective view illustratively showing an impeller according to another embodiment of the present invention.

FIG. 4 is an explanatory view partially showing an impeller according to another embodiment of the present invention.

FIG. 5 is a diagram showing a performance curve.

FIG. 6 is a perspective view illustratively showing a conventional impeller.

FIG. 7 is an explanatory view partially showing a conventional impeller.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Impeller 3 Rotating shaft 4 Blade 8 Fluid passage 41 Fluid receiving surface 41c Right-angled corner part to be formed by the trailing side and the outer side of the fluid receiving surface 42 Rear side 43 Outside side 43a Rear end 44 of the outside side 44 Outline 45 Inside side 45a Rear end of inside side 46 Side F1 Flow direction of water flow (fluid) W Width of fluid receiving surface

Claims (4)

(57) [Claims] 1. An impeller-type flowmeter according to claim 1, wherein a plurality of blades, which are arranged around a rotation axis and are inclined with respect to the axis of the rotation axis, are arranged in a fluid passage. Wherein the blade has a substantially rectangular fluid receiving surface, and a right angle to be formed by a rear side positioned downstream of the fluid receiving surface in the fluid flow direction and an outer side of the fluid receiving surface. Characterized in that the corner of (1) is omitted and the contour of the continuous portion between the rear side and the outer side is formed in an arc shape. 2. The method according to claim 1, wherein the right-angled corner formed by the rear side and the outer side is not cut off, and the area of the fluid receiving surface is not cut off. The impeller of the impeller type flow meter according to claim 1, wherein the area of the missing range is 0.2 to 8.0%. 3. A radius of the arc-shaped contour line is 2 to 3 mm.
The impeller of the impeller type flow meter according to claim 1 or 2, wherein 4. The impeller of an impeller type flow meter comprising a plurality of impellers provided around a rotating shaft and inclined at an interval with respect to the axis of the rotating shaft and arranged in a fluid passage. Wherein the blade has a fluid receiving surface, and a rear end located on the downstream side in the fluid flow direction on the inner side of the fluid receiving surface and a rear end of the outer side on the fluid receiving surface are An impeller for an impeller-type flow meter, wherein the impeller is continuous by sides having a convex arc-shaped contour line having a radius of the same dimension as a width dimension of the fluid receiving surface in a radial direction of a rotating shaft.