JP5579948B1 - Double box water meter - Google Patents

Abstract

【Task】
In a double box type water meter, the fluid resistance of the upward flow, which is a non-tangential flow with a reduced velocity flowing into the measurement chamber from the inflow nozzle arranged at a position far from the case inlet of the lower case, is reduced and smoothed. To allow inflow.
[Solution]
Each inflow nozzle N ₁ is composed of two nozzle forming bodies 17 arranged adjacent to each other and an upper plate portion 18 formed at an intermediate portion in the height direction of the peripheral wall portion 15 to form an upper surface 21 and left and right both surfaces 19, 19. The lower surface 1 and the lower inner case K ₁ are formed by exposing the bottom wall 16 at the back of the inflow nozzle N _1. It passes between the bottom wall 1c, 16, a multi chamber type water meter which functions as an upward flow guiding surface for performing guidance of the inflow nozzles N ₁ of the upflow flowing upward in the portion S ₂ the upward flow guiding surface Ft, the length between the center C of the lower edge and the lower inner case K ₁ is slightly shorter tapered surface than the length of the center C of the upper end edge and a lower inner case K ₁ It is set as the structure formed in.
[Selection] Figure 1

Description

  The present invention relates to a double box type water meter having a lower inner case in which an inflow nozzle is formed by a total of three surfaces including an upper surface and two left and right surfaces.

  In the double box type water meter (hereinafter simply referred to as “water meter”), the interior of the lower case is separated into an upstream chamber and a downstream chamber by a partition wall, and the lower half and upper half of the lower inner case A plurality of inflow nozzles and outflow nozzles are provided at predetermined intervals along the circumferential direction, and the central portion in the height direction of the lower inner case is supported by the partition wall, so that the inflow nozzle and the outflow nozzle are respectively The water flow which is arranged in the upstream chamber and the downstream chamber and flows into the lower inner case from the inlet nozzle in the upstream chamber is rotated from the outlet nozzle after rotating the impeller rotatably supported in the lower inner case. It is a water meter which measures the flow volume of the water flow which passed by the integrated rotation speed of the said impeller by flowing out into a downstream chamber.

  The lower inner case having the above-described configuration has a bottomed cylindrical shape, and includes a peripheral wall portion and a bottom wall portion, and a portion corresponding to the thickness of the lower half portion of the peripheral wall portion is tangent to the peripheral wall portion. A plurality of nozzle formation bodies slightly inclined with respect to the direction are formed in the vertical direction at a predetermined interval along the circumferential direction, and between the adjacent nozzle formation bodies, one of the outer peripheral surfaces of the bottom wall portion is formed. Each inflow nozzle is composed of two nozzle forming bodies arranged adjacent to each other, and an upper plate portion formed by the thickness of the peripheral wall portion, for a total of three surfaces, an upper surface and two left and right surfaces. The nozzle opening formed at the back of the inflow nozzle is formed by opening a portion connected to the bottom wall portion of the peripheral wall portion, and the nozzle opening is formed. The portion formed by the exposure of the bottom wall portion directly under the Functions as an upward flow guiding surface for performing the inflow guide flow flowing upward toward the inside bottom inner case from the bottom of the scan.

  As described above, as an inflow nozzle formed in the lower half portion of the lower inner case, a lower surface opened and formed by a total of three surfaces of an upper surface and two left and right surfaces is disclosed in Patent Documents 1 and 2. In addition to the original water flow in a slightly inclined direction with respect to the tangential direction of the impeller, the upward flow guide surface is not limited to the water flow directed upward or obliquely upward from the lower surface opening. It has the advantage that it is guided and flows into the lower inner case from the back of the inflow nozzle.

  Here, the water flow that flows into the inside from the case inlet of the lower case has a high ratio of the “direct flow” that flows directly into the inside from the inflow nozzle near the case inlet in the lower inner case. The inflow nozzle at a position far from the case inlet in the case of flowing through the narrow space between the bottom wall portion of the lower inner case and the lower case, and then flowing upward, the water flow related to the “direct flow” The ratio of the “upward flow” flowing into the lower inner case is increased. The ratio of “direct flow” becomes higher as the inflow nozzle arranged near the case inlet of the lower case among the plurality of inflow nozzles of the lower inner case, and conversely, the ratio of “upward flow” is Of the plurality of inflow nozzles of the lower inner case, the inflow nozzle disposed at a position farther from the case inlet of the lower case becomes higher.

  For this reason, the water flow related to the “upward flow” loses pressure due to the fluid resistance, and the velocity when flowing from the inflow nozzle into the lower inner case is reduced, but the inflow nozzle having the above-mentioned bottom surface opened. By using the lower inner case provided with a water flow having a reduced speed, it is easy to flow in.

  However, the upward flow guide surfaces described in Patent Documents 1 and 2 are respectively formed on the outer and inner sides of the inner peripheral surface of the peripheral wall portion of the lower inner case, and both are formed on the inner peripheral surface of the peripheral wall portion. Because it is formed in parallel, that is, it is formed perpendicular to the direction of the water flow, the fluid resistance when the water flow flows into the lower inner case increases, and the water flow with reduced speed is smooth. The inflow was inhibited.

Japanese Utility Model Publication No. 54-19180 Japanese Utility Model Publication No. 51-64670

  The present invention is a multi-box water meter having a lower inner case in which an inflow nozzle is formed by a total of three surfaces, an upper surface and two left and right surfaces, with a lower surface opened, and is disposed at a position far from a case inlet of a lower case. An object of the present invention is to reduce the fluid resistance of a water flow having a reduced velocity flowing into the lower inner case from the inflow nozzle, thereby enabling smooth inflow.

  The invention according to claim 1 for solving the above-mentioned problem is constituted by a peripheral wall portion and a bottom wall portion, and an impeller is rotatably accommodated and supported by a bottomed cylindrical lower inner case accommodated in the lower case. A plurality of inflow and outflow nozzles are respectively formed in the lower half and the upper half of the peripheral wall portion of the lower inner case, and the tangential direction of the impeller is approximately between the wall thicknesses of the peripheral wall portion. A plurality of nozzle forming bodies are formed in a vertical direction at a predetermined interval along the circumferential direction with slight inclination with respect to a part of the outer peripheral surface of the bottom wall portion between adjacent nozzle forming bodies. Each inflow nozzle is composed of two nozzle forming bodies arranged adjacent to each other, and an upper plate portion formed at an intermediate portion in the height direction of the peripheral wall portion. It is formed by a surface, and the bottom surface is opened. The surface formed by exposure of the bottom wall portion of the upper portion passes between the bottom wall portions of the lower case and the lower inner case, and guides the upward flow that flows upward at the inflow nozzle portion. A double box water meter functioning as a counterflow guide surface, wherein the upper flow guide surface has a length between its lower end edge and the center of the lower inner case, and its upper end edge and the center of the lower inner case. It is characterized by being formed in a taper surface slightly shorter than the length.

  The water flow flowing into the upstream chamber from the case inlet of the lower case flows into the lower inner case from a direction slightly inclined with respect to the tangential direction of the impeller from a plurality of inflow nozzles provided in the lower inner case. Then, by colliding with the impeller, the impeller is rotated and then flows out from the nozzle outlet to the downstream chamber. The water flow that flows into the upstream chamber includes a water flow that flows along the circumferential direction of the lower inner case (tangential flow) and a water flow that enters between the bottom wall portion of the lower inner case and the lower case (non-tangential flow). Yes, because the speed of the former tangential flow is high, the rate of direct flow into the inflow nozzle is high, and the speed of the latter non-tangential flow is reduced by the fluid resistance, and from the bottom wall of the lower inner case When trying to flow out to the outside, there is a high ratio of being guided by the upward flow guide surface to become an upward flow and flowing into the lower inner case.

  According to the invention of claim 1, the upward flow guide surface has a taper in which the length between the lower end edge and the center of the lower inner case is slightly shorter than the length between the upper end edge and the center of the lower inner case. In order to form an obtuse angle with the bottom surface of the bottom wall portion of the lower inner case, the upward flow guide surface formed in such a tapered surface is formed on the bottom wall of the lower inner case. The low-speed water flow that is about to flow out from between the bottom wall and the bottom wall of the lower case is caused by the original water flow (tangential flow) that is guided by the inflow nozzle and flows toward the inside of the lower inner case. Is changed upward, is guided by the inflow nozzle through the upper flow guide surface, and is accompanied by the original water flow (tangential flow) which is about to flow into the measuring chamber in the lower inner case. It flows into the inside. And since the upward flow guide surface forms an obtuse angle with the bottom surface of the bottom wall portion of the lower inner case, the fluid resistance when flowing in the upward flow is reduced, and as a result, the above-mentioned The flow of the upward flow at a low speed becomes smooth and easily flows into the lower inner case.

According to a second aspect of the present invention, in the first aspect of the invention, the upward flow guide surface having a tapered surface is formed only in one or a plurality of inflow nozzles on the side away from the case inlet of the lower case. It is a feature.

Position where the low-speed water flow that flows between the bottom wall portion of the lower inner case and the bottom wall portion of the lower case becomes an upward flow and is guided to the upper flow guide surface and flows into the lower inner case Is an inflow nozzle located on the side away from the case inlet of the lower case among the plurality of inflow nozzles provided in the lower inner case. For this reason, as in the invention of claim 2, when the upward flow guide surface having a tapered surface is formed only on one or a plurality of inflow nozzles on the side away from the case inlet of the lower case, the lower inner case The low-speed water flow that has flowed in between the bottom wall portion and the bottom wall portion of the lower case can be effectively flowed into the lower inner case.

The invention of claim 3 is characterized in that, in the invention of claim 1, the upward flow guide surface having a tapered surface is formed in all the inflow nozzles.

The upward flow guide surface having a tapered surface effectively acts on the inflow nozzle located on the side away from the case inlet of the lower case among the plurality of inflow nozzles provided in the lower inner case, As in the invention of claim 3, by providing the upward flow guide surface with a tapered surface for all the inflow nozzles, the water flow flowing between the bottom wall portion of the lower inner case and the lower case is The inflow nozzle easily flows into the lower inner case, and all the inflow nozzles including the upward flow guide surface have the same shape, so that the mold can be easily manufactured.

According to a fourth aspect of the present invention, in the invention of the second or third aspect, the taper angle of the tapered upward guide surface approaches the case inlet from the inflow nozzle farthest from the case inlet of the lower case. According to the above, it is characterized by decreasing gradually.

According to the invention of claim 4, the flow rate of the water flow (non-tangential flow) flowing between the bottom wall portion of the lower inner case and the bottom wall portion of the lower case decreases with increasing distance from the case inlet. Corresponding to the above, the inflow nozzle that is farther away from the case inlet of the lower case can effectively exert the function of the tapered surface upward flow guide surface, so the above-described low-speed water flow (non-tangential flow) Is effectively changed into an upward flow and is allowed to flow into the lower inner case.

  According to the present invention, the upward flow guide surface formed at the back of the inflow nozzle has a length between the lower end edge and the center of the lower inner case that is longer than the length between the upper end edge and the center of the lower inner case. However, the upward flow guide surface formed in such a tapered surface forms an obtuse angle with the bottom surface of the bottom wall portion of the lower inner case. For this reason, the low-speed water flow (non-tangential flow) that flows out from between the bottom wall portion of the lower inner case and the bottom wall portion of the lower case is guided to the inside of the lower inner case by the inflow nozzle. Accompanied by the original water flow (tangential flow) flowing in the direction, the flow direction is changed upward, and along with the original water flow (tangential flow) guided by the inflow nozzle through the upward flow guide surface And flows into the lower inner case. And since the upward flow guide surface forms an obtuse angle with the bottom surface of the bottom wall portion of the lower inner case, the flow of the upward flow as described above becomes smooth, It becomes easy to flow into the inside.

It is a longitudinal cross-sectional view of the water meter which concerns on this invention. (A), (b) is a perspective view, respectively lower inner case K ₁ of Example 1 from a different direction. It is a perspective view of the lower inner case K ₁ and the upper inner casing K _2. It is a bottom view of the lower inner case K _1. FIG. 5 is a sectional view taken along line XX in FIG. 4. FIG. 5 is a partial cross-sectional view taken along line YY in FIG. 4. It is a bottom view of the lower inner case K ₁ 'of the second embodiment of the present invention. It is a partially enlarged longitudinal sectional view of the inlet nozzle N ₁ '.

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

First, with reference to FIGS. 1 to 5, the basic configuration of a double box type water meter will be described, and thereafter, the characteristic part of the lower inner case K _{1 according} to the present invention will be described. Here, the present invention is characterized in part of the inflow nozzles N ₁ of the lower inner case K _1, water that has flowed from the case inlet 2 of the lower case 1 therein, the inflow nozzles N ₁ of the lower inner case K ₁ In the measuring chamber R inside the lower inner case K ₁ , after the impeller 12 is rotated, it is discharged through the outflow nozzle N ₂ to explain the part for measuring the integrated flow rate. Since the configuration in which the accumulated rotational speed of the impeller 12 is displayed on a display unit (not shown) is not directly related to the present invention, description of this part is omitted.

In FIG. 1, the lower case 1 includes a case inlet 2 and a case outlet 3, and the interior is separated into an upstream chamber 5 and a downstream chamber 6 by a partition wall 4, and is formed in the partition wall 4. With the substantially lower half of the lower inner case K ₁ inserted into the circular insertion opening 7, the support step 8 on the outer periphery of the lower inner case K ₁ faces the insertion opening 7 on the upper surface of the partition wall 4. By being supported by the portion, the lower inner case K ₁ is accommodated and arranged over both the upstream chamber 5 and the downstream chamber 6. _On the upper side of the lower inner case K _1, an upper inner case (also referred to as a “register box”) K ₂ with an integrated display unit (not shown) is disposed, so that the lower inner case K ₁ The top opening is closed. The upper part of the lower case 1 above the downstream chamber 6 is an upward projecting portion 1a formed in an annular shape, and the upper case 9 is screwed into the upper projecting portion 1a. Is closed by a lid 11 rotatably connected to the upper case 9 by hinge connection. The inside of the lower inner case K ₁ is a measuring chamber R, and the impeller 12 is rotatably disposed in the measuring chamber R via a pivot shaft 13. The pivot shaft 13 is supported by the shaft support portion 14 of the central portion of the bottom wall portion 18 of the lower inner case K _1.

As shown in FIGS. 2 to 6, the lower inner case K ₁ has a substantially cylindrical shape with a bottom, and includes a peripheral wall portion 15 and a bottom wall portion 16, and is substantially below the peripheral wall portion 15. A plurality of (eight in the embodiment) inflow nozzles N ₁ are formed at regular intervals along the circumferential direction in a portion corresponding to the thickness of the peripheral wall 15 in the half. In the upper half, a plurality (three in the embodiment) of outflow nozzles N ₂ are formed in communication with the inside and outside at regular intervals along the circumferential direction. The outflow nozzle N ₂ opens upward in the single state of the lower inner case K ₁ , but this upward opening is axially directed to the outer peripheral surface of the peripheral wall portion 31 of the upper inner case K _2. The lower protrusion 33a of the second rib 33 provided along is fitted and closed.

The inflow nozzle N ₁ connects the peripheral wall portion 15 and the bottom wall portion 16 along a direction in which the plurality of nozzle forming bodies 17 having a blade shape are slightly inclined with respect to the tangential direction of the peripheral wall portion 15. It is provided in such a form. As shown in FIGS. 5 and 6, the outer diameter of the bottom wall portion 16 corresponds to the inner diameter of the peripheral wall portion 15. The nozzle forming body 17 connects the outer peripheral surface of the bottom wall portion 16 and the lower end portion of the upper half portion of the peripheral wall portion 15, and the inflow nozzle N ₁ is an opposing surface of two adjacent nozzle forming bodies 17. (Left and right side surfaces) 19, 19 and a total of three surfaces including an upper surface 21 between two adjacent nozzle forming bodies 17 on the lower surface of the upper plate portion 18 provided in the intermediate portion in the height direction of the peripheral wall portion 15 Once formed, the bottom surface is open. The outer peripheral surface of the bottom wall portion 16 is exposed at the back of the inflow nozzle N ₁ , and the exposed surface is between the bottom wall portion 16 of the lower inner case K _{1 and} the bottom wall portion 1 c of the lower case 1. The upward flow guide surfaces Fp and Ft (see FIGS. 2 to 5) having a function of guiding the upward flow into the measuring chamber R by flowing upward into the measuring chamber R, and the upward flow Directly above the flow guide surfaces Fp and Ft, a plurality of nozzle forming bodies 17 are provided in the lower half of the peripheral wall portion 15 so that the thin thick portion remaining only on the inner peripheral side is opened in a square shape. A nozzle opening 22 is provided.

In the first embodiment, as shown in FIGS. 4 to 6, the plurality of upward flow guide surfaces Fp and Ft are both dimensionally larger than the inner peripheral surface 15 a of the peripheral wall portion 15 of the lower inner case K _1. Only E ₁ ) is arranged on the center side of the lower inner case K ₁ . Further, among the plurality of upward flow guide surfaces Fp, only one specific upward flow guide surface Ft arranged at the position farthest from the case inlet 2 of the lower case 1 is the following tapered surface. Yes. That is, the length (L ₁ ) connecting the lower edge of the upward flow guide surface Ft and the center (C) of the lower inner case K ₁ is the upper edge of the upward flow guide surface Ft and the lower inner case K. ₁ of the center (C) length connecting the (L ₂₎ slightly shorter than (L ₁ <L ₂₎ be formed on the tapered surface of the inclination angle (theta), this configuration, features of the present invention It is. All upflow guiding surface Fp rest except for certain upward flow guide surface Ft is parallel with the inner peripheral surface 15a of the peripheral wall 15 of the lower inner case K _1.

Further, as shown in FIG. 3, the inner case K includes a lower inner case K ₁ described above is disposed directly above the corresponding lower inner case K _1, while closing the upper opening of the lower inner case K ₁ The upper inner case K ₂ is provided with a display unit (not shown) for displaying the accumulated rotational speed of the impeller 12. As shown in FIG. 3, on the outer peripheral surface of the peripheral wall portion 31 of the upper inner case K ₂ , the plate-like first rib 32 reaching the lower end of the peripheral wall portion 31 and the lower end of the peripheral wall portion 31 are a predetermined length. A second rib 33 extending downward is formed in the axial direction at a predetermined interval along the circumferential direction. The second rib 33, have a substantially rectangular shape corresponding to the planar shape of the upper opening of the outlet nozzle N ₂ of the lower inner case K _1, fitting the positioning of the upper inner case K ₂ on the upper surface opening of the lower inner case K ₁ When the upper portion opening of the lower inner case K ₁ is closed by fitting the joint portions 34 together, the lower protrusion 33 a of the second rib 33 is formed on the upper opening of the outflow nozzle N ₂ of the lower inner case K ₁ . The upper opening of the lower inner case K ₁ is closed by the bottom wall portion 35 of the upper inner case K ₂ while being fitted to the portion. In FIG. 1, reference numeral 41 denotes a strainer provided in the case inlet 2 portion of the lower case 1.

Note that the upper half of the peripheral wall portion 15 of the lower inner case K ₁ and the second rib 33 portion of the upper inner case K ₂ have a hollow structure when cooling by resin injection molding. The present invention has a structure corresponding to resin injection molding for preventing “sinking” of the surface and preventing the surface from undulating, and is characterized by the presence of the upward flow guide surface Ft having a tapered surface shape. The structure is not directly related.

And the water flow which flowed into the upstream chamber 5 from the case inlet 2 of the lower case 1 is between the peripheral wall portion 15 of the lower inner case K ₁ and the lower peripheral wall portion 1b of the lower case 1 (see FIGS. 1 and 4). In the measuring chamber R through the original nozzle path that is close to the tangential direction of the inflow nozzle N ₁ and flows along the circumferential direction (the tangential direction of the peripheral wall 15 of the lower inner case K ₁ or the impeller 12). After passing between the directly flowing tangential flow S ₁ (see FIG. 4) and the bottom wall portion 16 of the lower inner case K _{1 and} the bottom wall portion 1c of the lower case 1, the bottom surface of the inflow nozzle N ₁ is reached. Immediately before, following the tangential flow S ₁ , the flow flows upward along the upward flow guide surfaces Fp and Ft, and then merges with the tangential flow S ₁ and indirectly into the measuring chamber R. There is an incoming upward flow S ₂ (see FIG. 1). As described in the section of “Prior Art”, the upward flow S ₂ is reduced in pressure by the fluid resistance as compared with the tangential flow S ₁ and the flow velocity is also reduced.

And most of the water flow that flows into the upstream chamber 5 from the case inlet 2 of the lower case 1 becomes a tangential flow S ₁ , passes through the original nozzle path of the inflow nozzle N ₁ , and passes through the lower inner case K ₁ . It flows directly into the internal measuring chamber R. Become tangential flow S _1, flow rate that flows from the inflow nozzles N ₁ to the metering chamber R is, among the plurality of inlet nozzles N _1, as close to the case flow inlet 2 of the lower case 1, often. On the other hand, the water flow that passes between the bottom wall portion 16 of the lower inner case K _{1 and} the bottom wall portion 1c of the lower case 1 without being the tangential flow S ₁ is reduced in pressure due to fluid resistance. The flow velocity is reduced, and in the portion of the inflow nozzle N ₁ far from the case inlet 2 of the lower case 1 among the plurality of inflow nozzles N ₁ , the upward flow is guided by the upward flow guide surfaces Fp and Ft. After becoming S ₂ , it is accompanied by the tangential flow S ₁ passing through the inflow nozzle N ₁ and flows into the measuring chamber R of the lower inner case K ₁ . Here, among the plurality of upward flow guide surfaces, the upward flow guide surface Ft farthest (separated from) the case inlet 2 of the lower case 1 is formed in the above-described tapered surface, and therefore, when inflow. The fluid resistance is reduced and smoothly flows into the measuring chamber R.

FIG. 7 shows a lower inner case K ₁ ′ of Embodiment 2 of the present invention. The lower inner case K ₁ ′ is a plurality of continuous upper-side guide surfaces provided at the back of each inflow nozzle N ₁ on the side farther (away from) the case inlet 2 of the lower case 1. Only the upward flow guide surface Ft is tapered, and the inclination angle of the tapered surface approaches the case inlet 2 from the inflow nozzle N ₁ farthest from the case inlet 2 of the lower case 1. It becomes small sequentially. The above configuration corresponds to the fact that the upward flow S ₂ is generated more as it is farther from the case inlet 2 of the lower case 1 in each inflow nozzle N ₁ .

Note that FIG. 4 and FIG. 6 is a irregular drawing was added and direction of the outer peripheral shape and tangential flow S ₁ of the lower case 1 to the bottom surface view of the lower inner case K _1, the lower inner case K ₁ and the lower case The swirl flow that flows between the lower peripheral wall portion 1b and the tangential flow S ₁ turns left.

Further, in Examples 1 and 2, the inclination angle (θ) of the upward flow guide surface Ft is 7.6 °, but the fluid resistance of the upward flow S ₂ is reduced to reduce the upward flow S _2. In view of the function of smoothly flowing into the measuring chamber R, 5 to 15 ° is desirable. When the inclination angle (θ) exceeds 15 °, the upward flow S ₂ inhibits the tangential flow S ₁ that is the original flow, disturbing the natural water flow in the portion of the inflow nozzle N ₁ , and the inclination angle This is because if (θ) is smaller than 5 °, the original function of the upward flow guide surface Ft described above cannot be achieved.

Further, in Examples 1 and 2, both including a tapered upward flow guide surfaces Ft, all upflow guide surface, the inner peripheral surface 15a of the peripheral wall 15 of the lower inner case K ₁ The upward flow S ₂ is likely to flow into the measuring chamber R by the dimension (E ₁ ) inside (the center side of the lower inner case K ₁ ). As shown in FIG. 8, all of the upward flow guide surfaces including the tapered upward flow guide surface Ft are dimensioned (E _{2) with} respect to the inner peripheral surface 15a of the peripheral wall portion 15 of the lower inner case K _1. It is also possible to arrange them only on the outside.

  In the first and second embodiments, of all the upward flow guide surfaces, only a specific upward flow guide surface is formed into a tapered surface, and the remaining upward flow guide surface is a peripheral wall portion of the lower inner case. However, it is also possible to form all the upward flow guide surfaces in a tapered shape.

Furthermore, although the features of the present invention are not directly related, in the _first and second embodiments, the upper surface of the outflow nozzle N ₂ of the lower inner case K ₁ is opened, and the upper inner case K ₂ Although it is the structure closed by fitting of the downward protrusion part 33a of the 2nd rib 33, as an outflow nozzle, you may form in the through-hole shape by which the upper surface was obstruct | occluded.

C: Center of the lower inner case Fp: General upward flow guide surface Ft: Tapered upward flow guide surface K: Inner case K ₁ : Lower inner case K ₂ : Upper inner case L ₁ : Upward flow guide length connecting the center of the lower edge and the lower inner case side L _2: length connecting the center of the upper edge and the lower inner case of upward flow guide surfaces N _1: inflow nozzles N _2: outlet nozzle S _1: Tangent flow S ₂ : Upward flow 1: Lower case 2: Case inflow port 12: Impeller 15: Peripheral wall portion 16: Bottom wall portion 17: Nozzle forming body 18: Upper plate portion 19: Left and right both sides of the inflow nozzle (adjacent Opposite surfaces of two nozzle forming bodies)
21: Upper surface of the inflow nozzle 22: Nozzle opening

Claims (4)

The impeller is rotatably accommodated and supported by a bottomed cylindrical lower inner case, which is composed of a peripheral wall portion and a bottom wall portion and is accommodated in the lower case, and the lower half portion and the upper portion of the peripheral wall portion of the lower inner case A plurality of inflow and outflow nozzles are formed in each half,
Between the substantially wall thickness of the peripheral wall portion, a plurality of nozzle forming bodies are formed in a vertical direction with a predetermined interval along the circumferential direction, with slight inclination with respect to the tangential direction of the impeller, and adjacent to each other. A part of the outer peripheral surface of the bottom wall portion is exposed between the nozzle forming bodies to be
Each inflow nozzle is formed by a total of three surfaces, that is, left and right surfaces and an upper surface, by two nozzle forming bodies arranged adjacent to each other and an upper plate portion formed at an intermediate portion in the height direction of the peripheral wall portion. The bottom surface is open,
The surface formed by the exposure of the bottom wall portion at the back of the inflow nozzle passes between the bottom wall portions of the lower case and the lower inner case, and flows upward in the inflow nozzle portion. A double-box water meter that functions as an upward flow guide surface for guiding
The upward flow guide surface is formed in a tapered surface whose length between the lower end edge and the center of the lower inner case is slightly shorter than the length between the upper end edge and the center of the lower inner case. Double box water meter. 2. The double box water meter according to claim 1, wherein the upward flow guide surface having a tapered surface is formed only on one or a plurality of inflow nozzles on the side away from the case inlet of the lower case. . The double box type water meter according to claim 1, wherein the upward flow guide surface of the tapered surface is formed in all the inflow nozzles. The taper angle of the upward flow guide surface of the tapered surface is gradually decreased from the inflow nozzle farthest from the case inlet of the lower case toward the case inlet. The double box type water meter according to 3.

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