JP2017009444A - Double case water meter, lower inner case, injection molding method thereof, and magnetic shielding structure of magnetic coupling shaft part in water meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To structure a lower inner case of a double case water meter so that the lower inner case can be injection-molded with only a pair of molding tools having a split structure and to facilitate assembling the lower inner case and a register box.SOLUTION: A lower inner case C and a register box B are positioned in a circumferential direction, and a positioning projection 28 is formed on one of a part close to a top surface opening of an annular peripheral wall part 23 of the lower inner case C and an insertion fitting part 38 of the register box B and a positioning recess 35 to be fitted to the positioning projection 28 is formed on the other in order to put the lower inner case C and the register box B into an assembled state through the insertion fitting part 38 of the register box B. The insertion fitting part 38 of the register box B closes an upper end opening of an outflow nozzle predeterminate opening N' of the lower inner case C in the state where the lower inner case C and the register box B are assembled, thereby forming an outflow nozzle opening N.SELECTED DRAWING: Figure 3

Description

  The present invention improves the moldability of the lower inner case, facilitates the assembly of the lower inner case and the register box, and reduces the coupling force of the magnetic coupling shaft portion to prevent fraud that reduces the integrated display. The present invention relates to a double-box water meter, a lower inner case and an injection molding method thereof, and a magnetic shielding structure of a magnetic coupling shaft portion of the water meter.

  The double box type water meter (hereinafter sometimes simply referred to as “water meter”) has a lower inner case in which an impeller is rotatably housed and held, and a register box in which a total display unit is built in a circumferential direction. In a state of being fitted along with each other and accommodated in the lower case, and a plurality of inflow and outflow nozzle openings are respectively formed in the lower and upper portions of the peripheral wall of the lower inner case. The water meter is configured to rotate the impeller by a water flow that flows into a measurement chamber inside the lower inner case and to measure the water flow through the outflow nozzle opening to the outside (Patent Document 1).

Both the lower inner case and the register box are formed by resin injection molding, and the lower inner case C ′ of the conventional structure has a bottomed cylindrical shape as shown in FIG. in the lower half of the annular wall portion 91, a plurality of inlet nozzle openings N ₁ is inclined with respect to the tangential direction, yet with are formed open to the bottom surface, the upper half of the annular wall portion 91 , number of small outflow nozzle opening N ₂ '' than the inflow nozzle opening N _1, a configuration which is provided to be inclined to the inlet nozzle opening N ₁ to the tangential direction in the opposite direction. The outflow nozzle opening N ₂ ″ is formed in a form penetrating in the inner and outer directions in the upper half portion of the annular peripheral wall portion 91. In FIG. 11, reference numeral 92 denotes a positioning recess for positioning the register box (not shown) in the circumferential direction with respect to the lower inner case C ′, and 93 denotes an annular peripheral wall portion 91 on its upper end surface. The meat stealing part opened and is shown.

For the injection molding of the lower inner case C ′, a pair of split molds for molding the entire lower inner case C ′ and a slide in a plane perpendicular to the approaching / separating direction of the pair of split molds. Thus, a plurality of slide dies for forming the outflow nozzle opening N ₂ ″ is required. For this reason, from the aspect of moldability of the lower inner case C ′, the injection mold is large and complicated, and the molding efficiency is lowered by the amount of use of the slide mold, and the production cost of the mold is also reduced. In addition to this, there is a problem that the area occupied by the mold at the molding site is increased. As a result, productivity per unit area at the molding site is deteriorated.

On the other hand, with respect to the surface of the shape of the lower inner case C ′ that can be formed, the bottom of the outflow nozzle opening N ₂ ″ formed by the slide mold, the upper surface (ceiling surface), and the concave portions for stealing the both inner side surfaces Cannot be molded. As a result, the thickness of the portion in contact with the outflow nozzle opening N ₂ ″ formed by the slide mold cannot be reduced, and “sink” occurs due to the difference in molding shrinkage during molding, resulting in unevenness on the surface. May occur. When the irregularities appear on the inflow nozzle opening N ₁ and the outflow nozzle opening N ₂ ″ through which water flows in and out, particularly on the inner surface of the inflow nozzle opening N ₁ , the irregularities become resistance to the water flow, thereby improving the measurement accuracy. Adversely affect.

  In Patent Document 2, a plurality of planned outflow nozzle openings that open to the upper end surface are formed in the upper half of the lower inner case, and the outer peripheral portion of the box body of the register box is below the lower end surface of the box body. A plurality of insertion fitting portions that are inserted and fitted into the respective outflow nozzle planned openings of the lower inner case, and in the state where the lower inner case and the register box are positioned in the circumferential direction, It has been disclosed that by inserting and fitting each insertion fitting portion of the register box into the upper end opening portion of each outflow nozzle planned opening of the lower inner case, an outflow nozzle opening in which the ceiling portion of the upper surface is closed is disclosed. . According to the above configuration, since the lower inner case can be injection-molded by only a pair of split molds without using a slide mold that forms the outflow nozzle opening, a gap portion is formed in the outer peripheral wall portion of the lower inner case. It becomes possible to reduce the thickness of the outer peripheral wall portion, and the above-mentioned problems of the lower inner case disclosed in Patent Document 1 can be solved.

  However, from the aspect of the assembly of the lower inner case and the register box, with the axial positioning of the register box and the lower inner case accurately aligned with the circumferential positioning of the two, the register box It is necessary to insert and fit multiple insertion fitting parts into the same number of planned outlet nozzle openings in the lower inner case at the same time, and this assembly work requires the experience and skill of the individual worker, making efficient assembly. Could not be done.

  On the other hand, as disclosed in Patent Document 2, a substantially bottomed cylindrical lower inner case in which the impeller is rotatably housed and held, and a substantially bottomed cylindrical register box in which the integrating display unit is housed And a magnet embedded in the upper end of the rotating shaft of the impeller in the lower inner case, and in the register box, on the axis of the rotating shaft. In the double box type water meter configured such that the input shaft rotates integrally with the rotating shaft by a magnetic connection with a magnet embedded in the lower end portion of the input shaft of the integrating display unit disposed in the lower display, Applying a magnetic force to each magnet part from the outside reduces the magnetic coupling force of each magnet, or eliminates the generation of the magnetic coupling force itself, thereby realizing the integrated display amount. It enables illegal to less than the amount used, it is also necessary to prevent this illegal.

JP 2000-234944 A JP 2014-231991 A

  The present invention has a structure in which the lower inner case of the double box type water meter can be injection-molded only with a split mold, facilitates the assembly of the lower inner case and the register box, and from the aspect of moldability, A large number of lower inner cases can be taken and integrated with a separate pivot shaft, and the rotation of the impeller of both the double box and single box water meter can be controlled by the magnetic coupling force. In the configuration for transmitting to the input shaft, an object is to prevent fraud in which the magnetic coupling force is reduced by an external magnetic force to reduce the displayed usage amount below the actual usage amount.

  The invention of claim 1 for solving the above-mentioned problem is a substantially bottomed cylindrical lower inner case in which an impeller is rotatably accommodated and held, and a substantially bottomed cylindrical register in which a total display unit is internally provided. The box is positioned and integrated along the circumferential direction and is accommodated in the lower case, and the inflow and outflow nozzle openings are provided in the lower half and upper half of the peripheral wall of the lower inner case. A plurality of openings are formed in the inner and outer directions of the lower inner case, and the impeller is rotated by the water flow flowing into the measuring chamber inside the lower inner case from the inflow nozzle opening, and the water flow is discharged from the outflow nozzle opening. A multi-box water meter configured to flow out to the outside and to be metered. In the upper half of the lower inner case, a plurality of pre-opening nozzle openings are formed and the register is registered. A circular insertion fitting portion having an outer diameter smaller than that of the outer peripheral wall portion and inserted into the insertion fitting space of the lower inner case is formed at a lower end portion of the lower inner case, and the lower inner case and the register box And the insertion fitting of the register box and the portion close to the upper surface opening of the annular circumferential wall portion of the lower inner case so as to be assembled together via the insertion fitting portion. A positioning convex part is formed on one side of the joint part, and a positioning concave part on which the positioning convex part is fitted is formed on the other side. When the lower inner case and the register box are assembled, the register box The insertion fitting portion is characterized in that the outflow nozzle opening is formed by closing the upper end opening of the outflow nozzle scheduled opening of the lower inner case.

  According to the first aspect of the present invention, the portion of the lower inner case where the inflow nozzle opening is formed is the outflow nozzle pre-opening that is open at the top, and has a structure that does not have an undercut portion. Molding is possible only with a pair of split molds without use. As a result, it is possible to provide a space in the outer peripheral wall portion or the like of the lower inner case to be molded, so that the wall thickness can be reduced and the sink surface can be prevented from occurring on the molding surface after molding. In the passage part, the flow of the water flow becomes smooth. On the other hand, from the molding surface, it is possible to mold with only a pair of molds with a split mold structure without using a slide mold. Is possible.

  In addition, when the insertion fitting portion of the register box is inserted and fitted into the insertion fitting space of the upper end portion of the outer peripheral wall portion of the lower inner case, when both are relatively pressed in a state where they are lightly pressed, In the middle, the positioning projection formed on one of the lower inner case and the register box is fitted into the positioning recess formed on the other, so that the insertion length of the insertion fitting portion of the register box is slightly increased. Thus, both are assembled in a state where the positioning along the circumferential direction is performed. As described above, skill and the like are not required for positioning and assembling the lower inner case and the register box in the circumferential direction, so that the assembling is facilitated. Further, in this assembled state, a part along the circumferential direction of the insertion fitting portion of the register box becomes a ceiling wall portion of the planned outflow nozzle opening of the lower inner case, the opening is closed, and the outflow nozzle An opening is formed.

  According to a second aspect of the present invention, in the first aspect of the invention, the insertion fitting portion of the register box includes an insertion fitting ring portion and a circular ring portion formed concentrically on the inner side thereof. A positioning recess is formed by removing a part of the portion, and the annular peripheral wall portion of the lower inner case is formed by inner and outer annular peripheral wall bodies integrally connected via a plurality of ribs. The peripheral wall body is formed lower than the outer annular peripheral wall body by a height corresponding to the height dimension of the insertion fitting portion, and is positioned in the upper end surface of the inner annular peripheral wall body and fitted into the positioning recess. The convex part protrudes upwards, It is characterized by the above-mentioned.

  According to the second aspect of the present invention, it is possible to form the positioning convex portion and the positioning concave portion in the state where both the outer peripheral wall portion of the lower inner case and the insertion fitting portion of the register box are thinned.

The invention of claim 3 is a method of injection-molding a lower inner case of a multi-box water meter using a pair of molds having a split mold structure and, if necessary, a slide mold,
The pivot shaft is integrated with the lower inner case by injecting molten resin into the cavity with the pivot shaft set in a pair of split molds.

  According to the invention of claim 3, since the lower inner case can be molded by the pair of molds having the split mold structure, the pivot shaft is set in the pair of molds having the split mold structure. By injecting the molten resin into the lower inner case, the pivot shaft can be integrated with the lower inner case, which eliminates the need for assembling the pivot shaft with respect to the lower inner case. Enhanced.

  The invention of claim 4 is a lower inner case of a multi-box water meter molded by the injection molding method of claim 3, and the strength of integration of the pivot shaft with respect to the lower inner case is increased, and the pivot with respect to the lower inner case Axial placement accuracy is increased.

  According to a fifth aspect of the present invention, the impeller is accommodated in the weighing chamber of the lower case, and the register box that accommodates the integration display unit is disposed above the weighing chamber and embedded in the upper end portion of the rotating shaft of the impeller. A water meter having a configuration in which the input shaft rotates integrally with the rotary shaft by a magnetic connection between the magnet and a magnet embedded in the lower end portion of the input shaft of the integration display unit disposed on the axis of the rotary shaft In the register box, a magnetic shielding member for preventing the magnetic force outside the lower case from reaching the magnetic coupling shaft portion to which the magnets are magnetically coupled is provided around the rotary shaft and the input shaft. It is characterized by being arranged in.

  According to the invention of claim 5, when a magnetic force is exerted on the magnetic coupling shaft portion from the outside of the lower case, the magnetic lines of force due to the magnetic force are cylindrical or ring plates arranged around the magnetic coupling shaft portion. It can prevent reaching to a magnetic connection axial part by flowing through the inside of a magnetic shield member. Thereby, the injustice which makes the integrated display amount of an integrated display unit smaller than the actual water supply usage amount can be prevented.

  The invention of claim 6 is the invention of claim 5, wherein the plurality of cylindrical magnetic shielding members having different outer diameters are concentrically with the rotation axis of the impeller at different positions along the radial direction of the register box. It is characterized by being arranged.

  According to the sixth aspect of the present invention, the plurality of cylindrical magnetic shielding members having different sizes can effectively shield the magnetism acting from the side with respect to the lower case, and the effect of preventing fraud is further enhanced. .

  According to a seventh aspect of the present invention, in the sixth aspect of the present invention, there is provided a flat ring-shaped magnet between two cylindrical magnetic shielding members having different outer diameters arranged at different positions along the radial direction of the register box. A shielding member is arranged.

  According to the seventh aspect of the present invention, the magnetism acting from both the side and the lower side of the lower case can be effectively shielded, and the effect of preventing fraud is further enhanced.

  According to the present invention, the lower inner case can be molded by a pair of molds having a split mold structure without using a slide mold by adopting a structure in which the upper surface of the planned outflow nozzle of the lower inner case is opened. As a result, it is possible to “multiple pieces” of the lower inner case which is a molded product. In addition, in the state where the insertion fitting portion of the register box is inserted and fitted into the fitting space portion at the upper end portion of the outer peripheral wall portion of the lower inner case, when both are relatively pressed in a state where they are lightly pressed, In the middle, the insertion length of the insertion fitting part of the register box is slightly increased by fitting the positioning convex part of the lower inner case into the positioning concave part of the register box, and both of them follow the circumferential direction. Since it is assembled in a state where it is positioned, assembly of the lower inner case and the register box is easy because it does not require skill, etc., and when both are assembled, the outflow nozzle of the lower inner case The upper surface of the planned opening is blocked by a part of the register box insertion fitting part in the circumferential direction, so that the outflow nozzle with the ceiling (upper part) closed is opened. There is formed.

  In addition, since the lower inner case can be formed by a pair of molds having a split mold structure, the lower inner case is injected by injecting molten resin into the cavity with the pivot shaft set in the pair of molds. The pivot shaft can be integrated with the case, so that it is not necessary to assemble the pivot shaft with respect to the lower inner case, and the placement accuracy of the pivot shaft with respect to the lower inner case is increased.

  Furthermore, a cylindrical or ring plate-shaped magnetic shielding member for preventing the magnetic force outside the water meter from reaching the magnetic coupling shaft portion to which the magnets are magnetically coupled, in the register box of the double box type water meter. However, in the configuration arranged around the rotation shaft and the input shaft, if a magnetic force is exerted on the magnetic coupling shaft portion from the outside of the lower case, the magnetic lines of force due to the magnetic force are formed around the magnetic coupling shaft portion. By flowing inside the cylindrical or ring plate-shaped magnetic shielding member, it can be prevented to reach the magnetic coupling shaft, and the total display amount of the total display unit is made smaller than the actual water use amount. It can prevent fraud.

It is a longitudinal cross-sectional view of the double box type water meter which concerns on this invention. It is a longitudinal cross-sectional view of the assembled state of the lower inner case C and the register box B. It is a perspective view of the separation state of lower inner case C and register box B. (A) is a top view of the lower inner case C, (b) is a sectional view taken along line XX of (a). (A) is a bottom view of the lower inner case C, and (b) is a cross-sectional view taken along line YY of (a). (A), (b) is a perspective view before and behind the assembly | attachment of the lower inner case C and the register box B. FIG. (A), (b) is the combination of a schematic plan view and longitudinal sectional view before and after the lower inner case C and the register box B are assembled. _{2 is} a schematic cross-sectional view of a pair of molds M ₁ and M _{2 having} a split mold structure for molding the lower inner case C. FIG. FIG. 4 is a schematic cross-sectional view of a pair of molds M ₁ and M ₂ and a slide mold M _{3 having} a split structure of the lower inner case C ′. (A), (b), (c) is a longitudinal cross-sectional view of the register box B, B ', B "which has a different magnetic shielding structure. It is a perspective view of the conventional lower inner case C '.

Hereinafter, the present invention will be described in more detail with reference to the best examples of the present invention. FIG. 1 is a longitudinal sectional view showing the entire water meter of the present invention. The lower case K ₁ is formed of metal and includes an inflow port 1 and an outflow port 2, and the inside is separated and formed into an upstream side chamber 4 and a downstream side chamber 5 by a ring disk-shaped partition wall 3. In a state where the substantially lower half portion of the lower inner case C is inserted into the circular opening 6 formed in the partition wall 3, the support step portion 7 on the outer periphery of the lower inner case C is in a portion facing the circular opening 6 in the partition wall 3. By being supported, the lower inner case C is accommodated and arranged over both the upstream chamber 4 and the downstream chamber 5. On the upper side of the lower inner case C, a register box B in which the integration display unit U is housed is disposed in an integrally assembled state, and a cover 9 is provided on the male screw portion 8 at the outer periphery of the upper end of the register box B. the upper case K ₂ is screwed.

A transparent glass plate 13 is disposed between the annular flange 11 provided inside the upper end portion of the upper case K _{2 made} of metal and the upper end surface of the register box B via a watertight packing 12, The register box B and the transparent glass plate 13 are integrated by the screwing tightening force of the upper case K ₂ to the register box B. Further, a register box height direction of the annular flange portion 14 provided in the middle of B, between the upper end surface of the lower case K _1, further watertight packing 15 is disposed on the lower casing K ₁ cylinder The male threaded portion 17 formed on the outer peripheral surface of the portion 16 and the annular fastening body 18 formed of metal are screwed together, so that the annular flange 19 inside the upper end portion of the annular fastening body 18 The annular flange 14 of the register box B is pressed downward, and the lower inner case C and the register box B are integrated with the partition wall 3 of the lower case K ₁ by the screwing tightening force of the annular tightening body 18. by being pressed against the lower case K _1, it is integrated and a lower inner case C and register box B.

The lower inner case C is an injection-molded product of resin, and as shown in FIGS. 1 to 3, has a bottomed short cylindrical schematic shape, and the hollow cylindrical portion inside thereof is It is a weighing room R. The supporting stepped portion 7 is formed in the central portion along the height direction of the outer peripheral portion of the lower inner case C, and a plurality of nozzle forming wall portions 21 are tangentially arranged at a portion below the supporting stepped portion 7. A space between the adjacent nozzle forming wall portions 21 formed in the circumferential direction along the direction inclined with respect to each other is an inflow nozzle opening N ₁ . The inflow nozzle opening N ₁ is abruptly narrower along the inflow direction, and the inner surface facing the inflow nozzle opening N ₁ is formed by two adjacent nozzle forming wall portions 21 and the inflow nozzle opening N _1. The ceiling surface (upper surface) of the nozzle opening N ₁ is formed by a bottom wall portion 22 of an outflow nozzle opening N ₂ described later, and the bottom surface is opened. As shown in FIG. 1, in a state where the lower inner case C are incorporated in the lower case K _1, inlet nozzle opening N ₁ is the upstream side chamber 4 of the lower case K _1, and communicates the inside and outside of the metering chamber R Yes.

An annular peripheral wall portion 23 is formed in a portion of the lower inner case C above the support stepped portion 7, and the annular peripheral wall portion 23 is spaced from the inflow nozzle opening N _{1 at} equal intervals along the circumferential direction. A small number of planned outflow nozzle openings N ₂ ′ are formed inclining in the direction opposite to the inflow nozzle opening N ₁ with respect to the tangential direction. The outflow nozzle scheduled opening N ₂ ′ opens along the inside and outside directions of the measuring chamber R, and can be formed by only a pair of forming molds M ₁ and M ₂ having a split structure, as will be described in detail later. In addition, an opening is also provided above the register box B. As will be described later, a circular ring-shaped insertion fitting ring portion 33 and a circular ring portion 34 formed at the lower end portion of the register box B are formed in an upper opening portion of the outflow nozzle scheduled opening N ₂ ′ of the lower inner case C. In the state where the lower inner case C and the register box B which are closed and integrated with a part in the circumferential direction of the insertion fitting portion 38 formed in the above are assembled in the lower case K ₁ , the outflow nozzle opening N ₂ is , and in the downstream side chamber 5 of the lower case K _1, it communicates the inside and outside of the metering chamber R. The bottom wall portion 22 of the outflow nozzle opening N ₂ in the lower inner case C is exposed in the state of the outflow nozzle scheduled opening N ₂ ′, and in the approach / separation direction of the pair of molds M ₁ and M _2. In order to eliminate the undercut portion along the lower inner case C, the lower inner case C opens not only in the annular peripheral wall portion 23 but also in the bottom wall portion 24 at the time of molding with the pair of molds M ₁ and M _2. It becomes possible to form each recessed part 25 and 26 which were made, and it becomes possible to steal the said annular surrounding wall part 23 and the bottom wall part 24, and to make it thin.

  The annular peripheral wall portion 23 is formed by inner and outer annular peripheral wall bodies 23a and 23b. The annular peripheral wall bodies 23a and 23b are connected by a connecting rib 27, and the concave portion 25 is interposed between the annular peripheral wall bodies 23a and 23b. Is formed. Since the insertion fitting portion 38 of the register box B is inserted and fitted inside the outer annular peripheral wall 23a that forms the annular peripheral wall 23 of the lower inner case C, the inner annular peripheral wall 23b is the outer annular peripheral wall 23a. Is lower by a length corresponding to the protrusion length (L) of the insertion fitting portion 38 of the register box B (see FIG. 5), and the space portion facing the upper surface opening in the lower inner case C is An insertion fitting space 30 into which the insertion fitting portion 38 of the box B is inserted and fitted is formed.

  Further, on the inner annular peripheral wall body 23b forming the annular peripheral wall portion 23 of the lower inner case C, positioning convex portions 28 for positioning the register box B in the circumferential direction with respect to the lower inner case C are provided along the radial direction. Only one point is formed to protrude upward.

Further, since the lower inner case C can be formed by a pair of molds M ₁ and M ₂ , the rotation shaft of the impeller A with respect to the lower inner case C when the lower inner case C is injection-molded. Since the pivot shaft 29 made of a metal such as stainless steel for supporting 51 can be integrally formed, the pivot shaft 29 is integrated with the lower inner case C in the molded state.

  On the other hand, the register box B is an injection-molded product of resin, and as shown in FIGS. 1, 3 and 5, the bottom wall portion 31 has a thick bottomed cylindrical shape, and has an internal space. The integrated display unit U is disposed in the portion, the annular flange 14 is formed in a portion near the upper end opening of the outer peripheral wall portion 32, and more than the annular flange 14 on the outer peripheral surface of the outer peripheral wall portion 32. The male screw portion 8 is formed in the upper portion. The thick bottom wall 31 has a circular ring shape which is smaller than the outer diameter of the outer peripheral wall 32 and is inserted and fitted inside the outer annular peripheral wall 23a constituting the annular peripheral wall 23 of the lower inner case C. The insertion fitting ring portion 33 protrudes downward, and another circular ring portion 34 having an outer diameter smaller than the inner diameter of the insertion fitting ring portion 33 is formed inside the insertion fitting ring portion 33. The insertion fitting ring portion 33 and the circular ring portion 34 constitute an insertion fitting portion 38 that is inserted and fitted into the insertion fitting space 30 of the lower inner case C. In one place along the circumferential direction of the circular ring portion 34, a positioning recess 35 is formed for positioning in the circumferential direction when the lower inner case C and the register box B are assembled. The positioning convex portion 28 of the lower inner case C is inserted and fitted into the positioning concave portion 35. In FIG. 5, reference numeral 36 denotes an accommodation space in which the integration display unit U is accommodated.

Next, an injection molding method of the lower inner case C will be described with reference to FIG. 8 is a diagram for explaining only the injection molding method of the lower inner case C. Therefore, the cavity 41 is schematically shown in relation to the molded product shown in FIGS. It is. Since the outflow nozzle planned opening N ₂ ′ formed in the upper half portion of the annular peripheral wall portion 23 of the lower inner case C has a structure that opens upward, a pair of parts separated along the axial direction of the pivot shaft 29. Molding is possible with the molds M ₁ and M ₂ . Therefore, as shown in FIG. 8, the metal pivot shaft 29 formed in advance is supported by the pair of molds M ₁ and M ₂ and set by the molds M ₁ and M _2. When the molten resin is injected into the cavity 41, the pivot shaft 29 is integrated with the lower inner case C to be molded. In addition, if the part 29a exposed to the cavity 41 in the pivot shaft 29 is knurled, the integrity with the molding resin is improved. This eliminates the need for a step of assembling the pivot shaft 29 with respect to the lower inner case C in the subsequent process, and also has an advantage that the arrangement accuracy of the pivot shaft 29 with respect to the lower inner case C can be improved. In FIG. _{8, M 2 a, M 2} b are flow nozzle will apertured formed portion of the annular wall portion 23 of the mold M _1, and respectively the general portion forming part, only by a pair of molds M _1, M ₂ It can be seen that the lower inner case C is molded, and the recesses 25 and 26 are freely provided in the annular peripheral wall portion 23 and the bottom wall portion 24 of the molded lower inner case C, so that the thickness can be reduced. In FIG. 8, P indicates the approaching / separating direction of the pair of molds M ₁ and M ₂ .

In order to assemble the lower inner case C and the register box B integrally, as shown in FIGS. 1, 3, 6, and 7, the rotating shaft 51 of the impeller A is attached to the pivot shaft 29 of the lower inner case C. By being supported, the impeller A is accommodated in the lower inner case C, and the insertion fitting space of the lower inner case C in a state where the integrated display unit U is accommodated in the accommodation space 36 of the register box B. In the state in which the insertion fitting portion 38 projecting downward from the bottom wall portion 31 of the register box B is inserted and fitted to 30, the positioning convex portion 28 provided on the inner annular peripheral wall body 23b of the lower inner case C. Is brought into contact with the lower end surface of the circular ring portion 34 of the register box B, thereby inserting the insertion fitting ring portion 3 of the register box B as shown in FIGS. 6 (a) and 7 (a). Height direction substantially half of the portion along the line (insertion fitting portion 38), will remain fitted into the inside of the outer annular wall member 23a of the lower inner case C. In addition, in the accommodation space 36 of the register box B, the integration display unit U is accommodated and arranged in a state where the circumferential positioning is performed. Therefore, in this state, when the lower inner case C and the register box B are relatively rotated while being pressed lightly so as to be close to each other, the positioning convex portion 28 of the lower inner case C becomes the positioning concave portion of the register box B. As shown in FIG. 2, FIG. 6 (b) and FIG. 7 (b), the outer annular peripheral wall of the lower inner case C is inserted and fitted into the member 35 in a state in which both are positioned in the circumferential direction. All of the insertion fitting ring portions 33 of the register box B are inserted and fitted inside the body 23a so that the outer peripheral lower end surface 31a of the bottom wall portion 31 of the register box B is the outer annular peripheral wall body 23a of the lower inner case C. by abutting the upper end surface 23a ₁ of, and a lower inner case C and register box B are assembled together. For this reason, since the lower inner case C and the register box B can be quickly assembled without requiring experience and skill in the circumferential alignment, the assembly work efficiency can be increased. . Accordingly, the arrangement of the plurality of outlet nozzles opening N ₂ for the first and second display units 61 and 62 of the integrated display unit U is set as.

Lower inner case C and register box B, as described above, the opening of the upper cylindrical portion 16 lower case K ₁ is inserted therein, the supporting step portion 7 of the lower inner case C is, the lower case K ₁ bulkhead 3, and in this state, the first and second display portions 61 and 62 of the integration display unit U accommodated in the accommodation space 36 of the register box B are in the correct positions with respect to the direction in which the water flows. are arranged, by the male screw portion 17 of the upper cylindrical portion 16 of the lower case K ₁ screwed annular clamping member 18, by its attached screwing clamping force, both B, C are integral to the lower case K ₁ Mounted on.

The water flow that has flowed into the upstream chamber 4 from the inlet ₁ of the lower case K ₁ passes into the measuring chamber R of the lower inner case C along the substantially tangential direction of the rotation circle of the impeller A through the plurality of inlet nozzle openings N _1. After flowing in and colliding with each blade 53 of the blade root A, the impeller A is rotated, and then flows out into the downstream chamber 5 through the plurality of outflow nozzle openings N ₂ , through the outlet 2. It is discharged to the outside of the lower case K ₁ Te.

The input shaft 71 of the integration display unit U is arranged on the shaft center of the rotating shaft 51 of the impeller A, and a magnet 52 embedded in the upper end portion of the rotating shaft 51 of the impeller A, and the lower end portion of the input shaft 71. The embedded magnet 72 is magnetically coupled to form a magnetic coupling shaft portion, and the input shaft 71 rotates integrally with the rotating shaft 51 of the impeller A. The rotation of the input shaft 71 is transmitted to the indicator rollers 63 constituting the first display portion 61 and the pointer gears 66 of the pointers 64 and 65 constituting the second display portion 62, thereby passing through the measuring chamber R. The flow rate is integrated and displayed. In the first display unit 61, up to 0.1 m ³ of the integrated flow rate is displayed as a roller, and less than 0.1 m ^{3 of the} integrated flow rate is displayed by the two hands 64 and 65 of the second display unit 62. In addition, in FIG. 6, 67 shows the pilot for detecting the water leak of a water meter.

  In the above embodiment, the positioning convex portion 28 is formed on the lower inner case C side, and the positioning concave portion 35 into which the positioning convex portion 28 is fitted is formed on the register box B side. The member in which the convex part 28 and the positioning recessed part 35 are formed can also be made reverse to the above.

Further, in the injection molding of the lower inner case C ′ having the conventional structure shown in FIG. 11, the pivot in the injection molding is performed in the same manner as the injection molding of the lower inner case C integrated with the pivot shaft 29 according to the present invention. The shaft 29 can be formed integrally. That is, as shown in FIG. 11, the lower inner case of the conventional structure C 'is the outflow nozzle openings N _2' to part 'of the undercut structure, forming part of the outflow nozzle opening N _2' ' In addition to the pair of molds M ₁ and M ₂ ′ having a split mold structure, it is essential to use a plurality of slide molds M ₃ that slide relative to the mold M ₂ ′. A plurality of slide-type M ₃ are, are disposed through the hollow cylindrical portion of the hollow bottomed cylindrical cavity 41 '. The slide direction Q of the slide mold M ₃ is a direction inclined with respect to the radial direction of the hollow bottomed cylindrical cavity 41 ′, but is in the radial direction of the cavity 41 ′ because of the illustrated relationship. . Also in the lower inner case C ′ of the conventional structure, the pivot shaft 29 is supported and set by the pair of molding dies M ₁ and M ₂ ′, so that the lower inner case in which the pivot shaft 29 is integrated at the time of molding. It can be seen that the case C ′ can be injection molded. In FIG. 9, M ₂ ′ a and M ₃ a indicate the outflow nozzle opening molding portion of the annular peripheral wall portion 91 in the molding die M ₂ ′ and the sliding die M ₃ , respectively, and M ₂ ′ b is the molding die M ₂ shows a general molded portion of the annular peripheral wall 91 in FIG.

  Further, since the rotation of the rotating shaft 51 of the impeller A is transmitted to the input shaft 71 of the integration display unit U by a magnetic coupling force, the magnetic transmission force is reduced by the action of an external magnetic force, or By preventing the generation of the magnetic transmission force itself, it is possible to cheat to make the integrated display amount smaller than the actual water consumption. In order to achieve fraud, the magnetic force of either the magnet 52 of the rotating shaft 51 of the impeller A or the magnet 72 of the input shaft 71 of the integrating display unit U may be reduced.

  Therefore, as shown in FIG. 1 and FIG. 10A, the gap between the outer peripheral wall portion 32 of the register box B and the peripheral wall portion 68 a of the storage box 68 of the integration display unit U corresponds to the gap. A cylindrical first magnetic shielding cylinder 81 having a thickness is arranged. Further, a frustoconical protrusion 39 is protruded inwardly at the center of the bottom wall 31 of the register box B, and the impeller A is formed in the recess formed by providing the protrusion 39. The magnet 52 at the tip of the rotating shaft 51 is disposed, and both the magnet 52 of the rotating shaft 51 of the impeller A and the magnet 72 of the input shaft 71 of the integrating display unit U are disposed in the vicinity of the protrusion 39. Has been. For this reason, a second magnetic shielding cylinder 82 made of a cylinder having a truncated cone shape is disposed outside the protruding portion 39. The first and second magnetic shielding cylinders 81 and 82 are made of a magnetic material such as metal. Even if the second magnetic shielding cylinder 82 is disposed in the vicinity of the magnets 52 and 72, there is no magnetic material between the magnets 52 and 72, so the magnetic coupling force between the magnets 52 and 72 is reduced. Absent. Naturally, each of the first and second magnetic shielding cylinders 81 and 82 is made of a magnetic material such as metal.

Therefore, in order to offset the magnetic force of the magnets 52 and 72, toward the respective magnets 52 and 72, also exerts a force toward the inside from the side of the lower case K ₁ of water meters, the large the field lines Since the portion flows inside the first and second magnetic shielding cylinders 81 and 82 and does not reach the magnets 52 and 72, the above-described fraud can be prevented. In particular, in the above structure, since the magnetic force from the outside can be prevented by the double cylinder structure, the fraud prevention effect is high.

FIGS. 10B and 10C show a magnetic shielding structure different from the above. FIG. 10B shows an inner peripheral surface of the outer peripheral wall portion 32, in which a first cylindrical portion 37 is integrally provided outside the protruding portion 39 provided to protrude inwardly on the bottom wall portion 31 of the register box B ′. The first magnetic shielding cylinder having an L-shaped cross section is formed by integrally providing a wide flange portion 83a at one end portion in the axial direction of the cylindrical body between the inner surface of the bottom wall portion 31 and the inner surface of the bottom wall portion 31. 83 are arranged, in cooperation with the second magnetic shielding cylinder 82 disposed outside of the projecting portion 39, the lower case K ₁ of water meters not laterally only, wide of the first magnetic shielding cylinder 83 Since the flange portion 83a is disposed below the magnet 72 embedded in the lower end portion of the input shaft 71, the flange portion 83a is configured to shield magnetism from below. Magnetism from below is shielded by the horizontal flange portion 83 a of the first magnetic shielding cylinder 83.

FIG. 10C shows that the second cylindrical portion 40 is formed inside the outer peripheral wall portion 32 of the register box B ″, and the cylindrical first magnetic shielding cylinder 81 is disposed between the two, and the bottom wall portion is formed. Between the first and second cylindrical portions 37, 40 on the inner surface of 31, a ring plate-shaped magnetic shielding plate 84 that shields magnetism from below the lower case K ₁ of the water meter is disposed.

Regarding the direction of magnetism exerted on the lower case of the water meter from the outside, all of the above magnetic shielding structures have a double-cylinder structure in the longitudinal sectional view. When the flange portion 83a or the ring-plate-shaped magnetic shielding plate 84 is disposed on the inner surface of the bottom wall portion 31 of the register box B ′, B ″, and the water of the first magnetic bill cylinder 83, the lower case K ₁ is large. Magnetic shielding from below is possible, and if space is possible, a magnetic shielding plate can be provided above the upper magnet 72 to enhance the magnetic shielding effect from above the water meter. It becomes.

  Here, the above-mentioned “magnetic shielding structure” of the magnetic coupling shaft portion is an example implemented in the magnetic coupling shaft portion of the double box type water meter, but according to the present invention, “magnetic shielding of the magnetic coupling shaft portion of the water meter” The implementation target of “Structure” is only a multi-box water meter with a structure in which the lower inner case and the register box housed in the lower case are assembled together in a state straddling both the upstream chamber and the downstream chamber. First, the measuring chamber in the lower case that measures the water flow and the register box that houses the integrating display unit are separated in a watertight state by a separate pressure receiving plate, and the rotation of the rotating shaft of the impeller is integrated into the integrating display unit. A single box water meter configured to be transmitted to the input shaft by a magnetic coupling force can also be implemented. Further, in a normally designed single box water meter, since two magnets that are magnetically connected to each other are disposed above the upper surface of the pressure receiving plate, a magnetic shielding member may be disposed on the upper surface of the contact pressure receiving plate. , Has a magnetic shielding effect.

A: Impeller
B: Register box
C: Lower inner case
K ₁ : Lower case M ₁ , M ₂ , M ₂ ': Mold with split mold structure
M ₃ : Slide type
N ₁ : Inflow nozzle opening
N ₂ : Outflow nozzle opening
N ₂ ': Outflow nozzle planned opening
R: Weighing room
23: The annular peripheral wall of the lower inner case
23a: outer annular peripheral wall body
23b: Inner annular peripheral wall body
28: Positioning convex portion of the lower inner case
29: Pivot shaft
30: Space for inserting and fitting the lower inner case
32: Outer wall of register box
33: Insertion fitting ring part
34: Circular ring part
35: Register box positioning recess
38: Insertion fitting part of register box
41: Cavity formed by a pair of molds 81, 83: First magnetic shielding cylinder
82: Second magnetic shielding cylinder
84: Magnetic shielding plate

Claims (7)

A substantially bottomed cylindrical lower inner case in which the impeller is rotatably housed and held, and a substantially bottomed cylindrical register box in which the integrating display unit is housed are positioned and integrated along the circumferential direction. In the lower case,
A plurality of inflow and outflow nozzle openings are formed in the lower and upper half portions of the peripheral wall of the lower inner case so as to open inward and outward of the lower inner case, and the inside of the lower inner case extends from the inflow nozzle opening. A double-box water meter configured to rotate and measure the impeller by flowing the water flow into the measuring chamber, and to flow the water flow to the outside through the outflow nozzle opening,
In the upper half of the lower inner case, there are a plurality of planned outflow nozzle openings whose upper surface is open, and the lower end of the register box has an outer diameter smaller than the outer peripheral wall, and the lower inner case is inserted into the lower inner case. A circular insertion fitting portion that is inserted and fitted into the joint space is formed,
Positioning in the circumferential direction of the lower inner case and the register box, a portion close to the upper surface opening of the annular peripheral wall portion of the lower inner case, in order to put both together through the insertion fitting portion, and On one side of the insertion fitting portion of the register box, a positioning convex portion is formed on the other side, and a positioning concave portion on which the positioning convex portion is fitted is formed.
In the state where the lower inner case and the register box are assembled, the insertion fitting portion of the register box closes the upper end opening of the outflow nozzle scheduled opening of the lower inner case, so that the outflow nozzle opening is formed. Features a double box water meter. The insertion fitting part of the register box is composed of an insertion fitting ring part and a circular ring part formed concentrically on the inner side thereof, and a part of the circular ring part is omitted so that a positioning recess is formed. Formed,
The annular inner peripheral wall portion of the lower inner case is formed by inner and outer annular peripheral wall bodies integrally connected via a plurality of ribs, and the inner annular peripheral wall body has a height corresponding to the height dimension of the insertion fitting portion. In addition, a positioning convex portion that is formed lower than the outer annular peripheral wall body and is fitted to the positioning concave portion is provided on the upper end surface of the inner annular peripheral wall body so as to protrude upward. The double box type water meter according to 1. A method of injection-molding a lower inner case of a double-box water meter using a pair of molds having a split mold structure and, if necessary, a slide mold,
A bottom inner of a multi-box water meter, wherein the pivot shaft is integrated with a lower inner case by injecting molten resin into the cavity with the pivot shaft set in a pair of molds Case injection molding method.   A lower inner case of a double box type water meter molded by the injection molding method according to claim 3. An impeller is accommodated in the weighing chamber of the lower case, and a register box that accommodates the integration display unit is disposed above the weighing chamber,
Due to the magnetic connection between the magnet embedded in the upper end of the rotating shaft of the impeller and the magnet embedded in the lower end of the input shaft of the integrating display unit disposed on the axis of the rotating shaft, the input shaft In the water meter configured to rotate integrally with the rotating shaft,
In the register box, a magnetic shielding member for preventing the magnetic force outside the lower case from reaching the magnetic coupling shaft portion to which the magnets are magnetically coupled is disposed around the rotating shaft and the input shaft. A magnetic shielding structure for a magnetic coupling shaft portion of a water meter, wherein   6. The plurality of cylindrical magnetic shielding members having different outer diameters are arranged concentrically with respect to the rotation axis of the impeller at different positions along the radial direction of the register box. Magnetic shielding structure of the magnetic coupling shaft of the water meter.   The flat ring-shaped magnetic shielding member is arranged between two cylindrical magnetic shielding members having different outer diameters arranged at different positions along the radial direction of the register box. The magnetic shielding structure of the magnetic coupling shaft part of the water meter according to 6.

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