JPH06331402A - Water meter - Google Patents

Abstract

PURPOSE:To reduce the error of a water meter by stabilizing the water flow flowing in the measuring chamber of the meter. CONSTITUTION:In a water meter having a water inlet 6 with an annular groove 6a in which the outer peripheral part of a strainer 5 is put on its inner peripheral surface and an incoming water passage 8 one end of which is connected to the inlet 6 at a prescribed angle adjacently to the groove 6a and the other end of which is communicated with a measuring chamber housing an impeller in a rotatable state, the passage 8 side edge section of the groove 6a which is protruded inward along the radial direction of the inlet 6 in a state where the edge section is separated from the outer peripheral section of the strainer 5 is formed in a straightening surface which smoothly continues toward the inner peripheral surface of the passage 8 at one end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a water meter, particularly a tangential flow impeller type single box type water meter.

[0002]

2. Description of the Related Art A known tangential flow impeller type single box type water meter generally has a structure as shown in FIG. In FIG. 5, (1) is a lower case having a measuring chamber (2) surrounded by a bottomed cylindrical side surface, and a pivot (3) is erected at the center of the bottom surface of the measuring chamber (2). An impeller (4) having several blades (4a) radially attached to a shaft (4b) is rotatably supported by a pivot (3). Lower case (1)
The water inlet (6) and the water outlet (7) each having an annular groove (6a) into which the strainer (5) is fitted are formed on both sides of the lower part of FIG.
As shown in, the water is disposed so as to be slightly deviated from the center of the measuring chamber (2) to one side, and the water inlet (6) communicates with the measuring chamber (2), and the water outlet ( The outlet channel (9) communicating between 7) and the measuring chamber (2) is formed obliquely to one side so that it is substantially tangential to the tip of the blade (4a) of the impeller (4). Has been done. A disk-shaped upper base plate (10) is fitted and supported in the upper opening of the lower case (1), and several pillars (1
1) is installed vertically. A disc-shaped lower base plate (12) is fixed to the lower ends of several columns (11), and an indicator gear mechanism (14) is provided in a space (13) between the upper base plate (10) and the lower base plate (12). ) Is installed. Upper base plate (10) and lower base plate (12)
In the space (13) between them, the upper end of the shaft (4b) of the impeller (4) is projected through the shaft hole (15) formed in the center of the lower base plate (13). The shaft (4
A pinion (16) which is appropriately meshed with the instruction gear mechanism (14) is integrally formed at the upper end of b). A recess (17) is formed on the upper surface of the upper base plate (10).
A scale plate (18) provided with a printed scale is printed or engraved on the bottom surface of 7) and a predetermined pointer shaft (not shown) is inserted from the indicator gear mechanism (14) into the recess (17). The needles (19) for instructing the scale of the scale plate (18) are attached to the upper ends of the respective pointer shafts so as to project properly. A transparent glass plate (20) made of a disc-shaped tempered glass is placed on the upper end of the upper base plate (10) via a lower gasket (21). The upper case (23) having the flange (23a) pressed through the upper gasket (22) is screwed onto the screw portion formed on the outer periphery of the upper portion of the lower case (1), whereby the lower case (1) An upper base plate (10) fitted and supported in the upper end opening portion and a transparent glass plate (20) placed on the upper base plate (10) are fastened and fixed to the lower case (1).

When the water meter is connected to a predetermined position of a water pipe, water flows from the water inlet (6) of the lower case (1) through the strainer (5) and the water inlet (8) into the measuring chamber (2). The water flows in, the impeller (8) is rotated by the flow of the water, and flows out from the water outlet (7) through the water outlet (9). When the impeller (8) rotates due to the flow of water, the pointer (19) rotates via the instruction gear mechanism (14) to instruct measurement of the water flow rate.

[0004]

By the way, in the above water meter, the difference between the water quantity indicated by the pointer (19) and the actual water quantity passed through should be as small as possible. However, the shape, dimensional accuracy, and assembly accuracy of each part of the water meter should be as small as possible. Due to the variation of, some error (equipment error) is unavoidable. Since this instrumental difference is different for each water meter, it cannot be uniformly adjusted by the adjusting mechanism in the water meter. For this reason, it is important to reduce the variation degree of the instrumental error for each water meter, that is, how to reduce the standard deviation.

However, in the above water meter, the water inlet (8) of the lower case (1) is inclined at a predetermined angle with respect to the water inlet (6), and the strainer (5) is fitted. Since the stepped surface (24) is formed by the annular groove (6a) for the purpose (see FIGS. 7 and 8), the water flowing from the water inlet (6) changes its flow direction to the water inlet (8). When entering, the water that collides with the step surface (24) generates a vortex there, and this vortex is brought to the measuring chamber (2) to disturb the normal flow of water, affecting the rotation of the impeller (4). As a result, it was found that there was a large variation due to the water meter error.

The present invention has been proposed in view of the above problems of the conventional water meter, and an object thereof is to provide a water meter capable of improving the instrumental error performance.

[0007]

In order to achieve the above-mentioned object, the present invention has a water inlet having an annular groove formed on the inner peripheral surface for fitting the outer peripheral portion of a strainer, and an annular groove of the water inlet at one end. Is adjacent to and connected at a predetermined angle,
In a water meter having the water inlet channel, the other end of which is connected to a measuring chamber that rotatably accommodates an impeller, an edge portion of the annular groove on the water inlet channel side, separated from an outer peripheral portion of the strainer. The edge portion that protrudes inward in the radial direction of the water inlet is a straightening surface that smoothly continues toward the inner peripheral surface at one end of the water inlet passage.

[0008]

With the above structure, even if water collides with a portion of the edge of the annular groove on the water inlet side which is separated from the outer periphery of the strainer and protrudes inward in the radial direction of the water inlet, the water is swirled by the rectifying surface. The generation of water was suppressed, the flow of water to the measuring chamber was stabilized, the variation in instrumental error was reduced, and the instrumental error performance could be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an enlarged transverse sectional view showing a water inlet portion of a water meter according to the present invention, and FIG. 2 is a side view of FIG.

As shown in FIG. 1 and FIG. 2, the water meter of the present invention has a water inlet (8) side of an annular groove (6a) formed in the inner peripheral surface of the water inlet (6) of the lower case (1). At the edge portion of the inlet of the strainer (5), which is separated from the outer periphery of the strainer (5) and protrudes inward in the radial direction of the water inlet (6), the flow is smoothly continuous toward one end of the water inlet (8). It has a structure with a face (25) formed.

The rectifying surface (25) is, for example, as shown in FIG. 3, inserted into the water inlet (6) at the tip of a drill (26) which performs a cutting and rotating motion by an appropriate rotation driving means. The edge of the annular groove (6a) at the edge of the annular groove (6a) on the side of the water inlet (8) is chamfered away from the outer periphery of the strainer (5) at the blade edge of (26) and protruding radially inward of the water inlet (6). It is formed by

Since the water meter of the present invention has the above-mentioned structure, when the water flowing from the water inlet (6) of the lower case (1) changes its direction and flows into the water inlet (8), Even if water collides with a portion of the edge of the annular groove (6a) on the water inlet (8) side, which is separated from the outer periphery of the strainer (5) and protrudes inward in the radial direction of the water inlet (6), the flow is rectified. Generation of vortices is suppressed by the surface (25), and the flow of water to the measuring chamber (2) can be stabilized. Therefore, the influence of the vortex on the rotation of the impeller (4) is reduced, and the variation degree of the instrumental error can be reduced.

[0014]

[Table 1]

[0015]

[Table 2]

The above Tables 1 and 2 show the water flow test data of the water meter of the present invention and the conventional water meter. The data are provided to the water flow test apparatus for each of the 30 water meters of the present invention and the conventional water meter. It was attached to a water flow rate, and a water flow test was conducted at a water flow rate of 1000 / h.
Table 1 shows the water flow test data of the water meter of the present invention, and Table 2 shows the water flow test data of the conventional water meter.
The numbers in the table are for each water meter No. By showing the instrumental error of 1 to 30 as a percentage [(meter displayed flow rate-actually-passed water amount) / (actually-passed water amount) x 100], it was verified that the water meter of the present invention has small instrumental error. There is.

FIG. 4 is a graph showing the instrumental difference performances of the water meter of the present invention and the conventional water meter in a comparative manner, which is based on the water flow test data (Table 1 and Table 2), and the instrumental error accuracy is determined by a predetermined mathematical formula. The solid line shows the water meter of the present invention, and the dotted line shows the conventional water meter. In FIG. 4, the vertical axis represents the standard deviation σ of the instrumental error accuracy, the horizontal axis represents the number of tests, and the one-dot and two-dot chain lines parallel to the horizontal axis represent the standard deviation σ of the instrumental error accuracy. Upper control limit control line and ideal control line.

The conventional water meter has a standard deviation σ of instrumental accuracy.
Is 0.6 to 0.8 and exceeds the upper control limit control line of the target value (σ = 0.4), whereas the water meter of the present invention has a standard deviation σ of instrumental error accuracy of 0. The target value was achieved at 4 or less, and it can be seen that this improves the instrumental error performance of the water meter of the present invention.

In the above embodiment, the rectifying surface (25) is formed by chamfering by drilling, but the present invention is not limited to this and may be a smooth curved surface by polishing or the like.

[0020]

As described above, according to the present invention, the edge of the annular groove formed on the inner peripheral surface of the lower case on the inlet channel side is spaced apart from the outer peripheral portion of the strainer and protrudes inward in the radial direction of the inlet port. By forming a rectifying surface in the part where the water flow is generated, the generation of vortices in the water entry part is suppressed and the flow of water to the measuring chamber is stabilized, which reduces variations in instrumental error and improves instrumental error performance. be able to.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a water inlet part of a water meter according to the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is an explanatory diagram showing a method for forming a chamfered portion.

FIG. 4 is a graph chart comparing and displaying the instrumental difference performance of the water meter of the present invention and the conventional water meter.

FIG. 5 is a vertical cross-sectional view of a conventional representative tangential flow impeller type single box type water meter.

6 is a cross-sectional view of FIG.

FIG. 7 is an enlarged cross-sectional view showing a water inlet of a conventional water meter.

FIG. 8 is a side view of FIG. 7.

[Explanation of symbols]

 1 Lower case 2 Measuring chamber 4 Impeller 6 Water inlet 5 Strainer 8 Water inlet 24 Stepped surface 25 Straightening surface 26 Drill

Claims (1)

[Claims] 1. A water inlet having an annular groove formed in the inner peripheral surface thereof, which fits the outer peripheral portion of the strainer, and one end of which is adjacent to the annular groove of the water inlet and forms a predetermined angle, and In a water meter having the water inlet channel, the other end of which is connected to a measuring chamber that rotatably accommodates an impeller, an edge portion of the annular groove on the water inlet channel side, separated from an outer peripheral portion of the strainer. A water meter, wherein an edge portion of the water inlet that protrudes inward in the radial direction is a straightening surface that smoothly continues toward the inner peripheral surface at one end of the water inlet passage.